Complete Source Code | C Language Design and Implementation of Employee Attendance System

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Main Content

System Overview

This is a simple employee attendance management system designed and implemented in C language, allowing for the recording and querying of employee attendance information, including check-in, check-out, leave requests, and attendance statistics.

System Design

1. Data Structures:

  • The Employee structure stores basic employee information
  • The AttendanceRecord structure stores attendance records
  • The AttendanceSystem structure manages all system data

2. Main Functions:

  • Add employee information
  • Check-in/Check-out records
  • Leave application
  • Attendance record query
  • Attendance report generation
  • Data persistent storage

Function Flowchart

Start
  |
Initialize System
  |
Display Main Menu
  |
Input Selection
  |
+----------------+----------------+----------------+----------------+----------------+
|                |                |                |                |                |
Check-in(1)     Check-out(2)    Leave(3)       Query Records(4) Statistics(5) Exit(0)
|                |                |                |                |                |
Record Check-in Time Record Check-out Time Record Leave Info Display Attendance Records Display Attendance Statistics Save Data
|                |                |                |                |                |
+----------------+----------------+----------------+----------------+----------------+
  |
Save Data
  |
End

Function Description

  1. Add Employee: Input employee ID, name, and department information, the system will check if the ID is duplicated
  2. Check-in: Record the employee’s work start time, automatically get the current time
  3. Check-out: Record the employee’s work end time, automatically get the current time
  4. Leave: Employees can apply for personal leave, sick leave, or annual leave, and specify the reason
  5. Query Records: Query specific employee attendance records by time range
  6. Generate Report: Statistics of all employees’ attendance in the specified time period

User Instructions

  1. The program will automatically load previously saved data upon startup
  2. Select the operation to be performed through the menu
  3. Input the corresponding information as prompted
  4. All data will be automatically saved to a file when exiting the program

Complete Code

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

// Define Employee structure
typedef struct {
    int id;
    char name[50];
    char department[50];
} Employee;

// Define Attendance Record structure
typedef struct {
    int employeeId;
    char date[11]; // YYYY-MM-DD
    char checkIn[6]; // HH:MM
    char checkOut[6]; // HH:MM
    int leaveType; // 0: No Leave, 1: Personal Leave, 2: Sick Leave, 3: Annual Leave
    char remarks[100];
} AttendanceRecord;

// Define system data structure
typedef struct {
    Employee* employees;
    AttendanceRecord* records;
    int employeeCount;
    int recordCount;
    int maxEmployees;
    int maxRecords;
} AttendanceSystem;

// Function declarations
void initializeSystem(AttendanceSystem* system, int maxEmployees, int maxRecords);
void freeSystem(AttendanceSystem* system);
void displayMenu();
void addEmployee(AttendanceSystem* system);
void checkIn(AttendanceSystem* system);
void checkOut(AttendanceSystem* system);
void applyLeave(AttendanceSystem* system);
void queryRecords(AttendanceSystem* system);
void generateReport(AttendanceSystem* system);
void saveData(AttendanceSystem* system);
void loadData(AttendanceSystem* system);
int findEmployeeById(AttendanceSystem* system, int id);
int findRecord(AttendanceSystem* system, int employeeId, const char* date);
void getCurrentDate(char* date);
void getCurrentTime(char* time);

int main() {
    AttendanceSystem system;
    int choice;

    // Initialize system
    initializeSystem(&system, 100, 1000);

    // Load data
    loadData(&system);

    printf("Welcome to the Employee Attendance Management System!\n");

    do {
        displayMenu();
        printf("Please select an operation: ");
        scanf("%d", &choice);

        switch(choice) {
            case 1:
                addEmployee(&system);
                break;
            case 2:
                checkIn(&system);
                break;
            case 3:
                checkOut(&system);
                break;
            case 4:
                applyLeave(&system);
                break;
            case 5:
                queryRecords(&system);
                break;
            case 6:
                generateReport(&system);
                break;
            case 0:
                printf("Thank you for using the Employee Attendance Management System!\n");
                break;
            default:
                printf("Invalid selection, please re-enter!\n");
        }
    } while(choice != 0);

    // Save data
    saveData(&system);

    // Free system resources
    freeSystem(&system);

    return 0;
}

// Initialize system
void initializeSystem(AttendanceSystem* system, int maxEmployees, int maxRecords) {
    system->employees = (Employee*)malloc(maxEmployees * sizeof(Employee));
    system->records = (AttendanceRecord*)malloc(maxRecords * sizeof(AttendanceRecord));
    system->employeeCount = 0;
    system->recordCount = 0;
    system->maxEmployees = maxEmployees;
    system->maxRecords = maxRecords;
}

// Free system resources
void freeSystem(AttendanceSystem* system) {
    free(system->employees);
    free(system->records);
}

// Display menu
void displayMenu() {
    printf("\n===== Employee Attendance Management System =====\n");
    printf("1. Add Employee\n");
    printf("2. Check-in\n");
    printf("3. Check-out\n");
    printf("4. Leave\n");
    printf("5. Query Attendance Records\n");
    printf("6. Generate Attendance Report\n");
    printf("0. Exit System\n");
    printf("============================\n");
}

// Add employee
void addEmployee(AttendanceSystem* system) {
    if(system->employeeCount >= system->maxEmployees) {
        printf("Employee limit reached, cannot add new employee!\n");
        return;
    }

    Employee newEmployee;

    printf("Please enter employee ID: ");
    scanf("%d", &newEmployee.id);

    // Check if employee ID already exists
    if(findEmployeeById(system, newEmployee.id) != -1) {
        printf("Employee ID already exists!\n");
        return;
    }

    printf("Please enter employee name: ");
    scanf("%s", newEmployee.name);

    printf("Please enter employee department: ");
    scanf("%s", newEmployee.department);

    system->employees[system->employeeCount] = newEmployee;
    system->employeeCount++;

    printf("Employee added successfully!\n");
}

// Check-in
void checkIn(AttendanceSystem* system) {
    int employeeId;
    char date[11];
    char time[6];

    printf("Please enter employee ID: ");
    scanf("%d", &employeeId);

    int employeeIndex = findEmployeeById(system, employeeId);
    if(employeeIndex == -1) {
        printf("Employee does not exist!\n");
        return;
    }

    getCurrentDate(date);
    getCurrentTime(time);

    int recordIndex = findRecord(system, employeeId, date);
    if(recordIndex == -1) {
        // Create new record
        if(system->recordCount >= system->maxRecords) {
            printf("Attendance record limit reached!\n");
            return;
        }

        AttendanceRecord newRecord;
        newRecord.employeeId = employeeId;
        strcpy(newRecord.date, date);
        strcpy(newRecord.checkIn, time);
        strcpy(newRecord.checkOut, "00:00");
        newRecord.leaveType = 0;
        strcpy(newRecord.remarks, "Check-in");

        system->records[system->recordCount] = newRecord;
        system->recordCount++;

        printf("Check-in successful! Time: %s %s\n", date, time);
    } else {
        // Update existing record
        if(strcmp(system->records[recordIndex].checkIn, "00:00") != 0) {
            printf("Already checked in today! Check-in time: %s\n", system->records[recordIndex].checkIn);
            return;
        }

        strcpy(system->records[recordIndex].checkIn, time);
        printf("Check-in successful! Time: %s %s\n", date, time);
    }
}

// Check-out
void checkOut(AttendanceSystem* system) {
    int employeeId;
    char date[11];
    char time[6];

    printf("Please enter employee ID: ");
    scanf("%d", &employeeId);

    int employeeIndex = findEmployeeById(system, employeeId);
    if(employeeIndex == -1) {
        printf("Employee does not exist!\n");
        return;
    }

    getCurrentDate(date);
    getCurrentTime(time);

    int recordIndex = findRecord(system, employeeId, date);
    if(recordIndex == -1) {
        printf("Please check in today first!\n");
        return;
    }

    if(strcmp(system->records[recordIndex].checkOut, "00:00") != 0) {
        printf("Already checked out today! Check-out time: %s\n", system->records[recordIndex].checkOut);
        return;
    }

    strcpy(system->records[recordIndex].checkOut, time);
    strcat(system->records[recordIndex].remarks, ", Check-out");

    printf("Check-out successful! Time: %s %s\n", date, time);
}

// Leave
void applyLeave(AttendanceSystem* system) {
    int employeeId;
    char date[11];
    int leaveType;
    char remarks[100];

    printf("Please enter employee ID: ");
    scanf("%d", &employeeId);

    int employeeIndex = findEmployeeById(system, employeeId);
    if(employeeIndex == -1) {
        printf("Employee does not exist!\n");
        return;
    }

    printf("Please enter leave date (YYYY-MM-DD): ");
    scanf("%s", date);

    printf("Please select leave type (1. Personal Leave 2. Sick Leave 3. Annual Leave): ");
    scanf("%d", &leaveType);

    printf("Please enter leave reason: ");
    scanf("%s", remarks);

    int recordIndex = findRecord(system, employeeId, date);
    if(recordIndex == -1) {
        // Create new record
        if(system->recordCount >= system->maxRecords) {
            printf("Attendance record limit reached!\n");
            return;
        }

        AttendanceRecord newRecord;
        newRecord.employeeId = employeeId;
        strcpy(newRecord.date, date);
        strcpy(newRecord.checkIn, "00:00");
        strcpy(newRecord.checkOut, "00:00");
        newRecord.leaveType = leaveType;
        strcpy(newRecord.remarks, remarks);

        system->records[system->recordCount] = newRecord;
        system->recordCount++;
    } else {
        // Update existing record
        system->records[recordIndex].leaveType = leaveType;
        strcpy(system->records[recordIndex].remarks, remarks);
    }

    printf("Leave application submitted successfully!\n");
}

// Query attendance records
void queryRecords(AttendanceSystem* system) {
    int employeeId;
    char startDate[11], endDate[11];

    printf("Please enter employee ID: ");
    scanf("%d", &employeeId);

    int employeeIndex = findEmployeeById(system, employeeId);
    if(employeeIndex == -1) {
        printf("Employee does not exist!\n");
        return;
    }

    printf("Please enter start date (YYYY-MM-DD): ");
    scanf("%s", startDate);

    printf("Please enter end date (YYYY-MM-DD): ");
    scanf("%s", endDate);

    printf("\nAttendance records for %s (%s to %s):\n", 
           system->employees[employeeIndex].name, startDate, endDate);
    printf("Date\t\tCheck-in Time\tCheck-out Time\tLeave Type\tRemarks\n");

    int found = 0;
    for(int i = 0; i < system->recordCount; i++) {
        if(system->records[i].employeeId == employeeId &&
           strcmp(system->records[i].date, startDate) >= 0 &&
           strcmp(system->records[i].date, endDate) <= 0) {

            char* leaveTypeStr;
            switch(system->records[i].leaveType) {
                case 0: leaveTypeStr = "None"; break;
                case 1: leaveTypeStr = "Personal Leave"; break;
                case 2: leaveTypeStr = "Sick Leave"; break;
                case 3: leaveTypeStr = "Annual Leave"; break;
                default: leaveTypeStr = "Unknown";
            }

            printf("%s\t%s\t\t%s\t\t%s\t\t%s\n", 
                   system->records[i].date,
                   system->records[i].checkIn,
                   system->records[i].checkOut,
                   leaveTypeStr,
                   system->records[i].remarks);
            found = 1;
        }
    }

    if(!found) {
        printf("No attendance records for this time period!\n");
    }
}

// Generate attendance report
void generateReport(AttendanceSystem* system) {
    char startDate[11], endDate[11];

    printf("Please enter start date (YYYY-MM-DD): ");
    scanf("%s", startDate);

    printf("Please enter end date (YYYY-MM-DD): ");
    scanf("%s", endDate);

    printf("\nAttendance Report (%s to %s):\n", startDate, endDate);
    printf("Employee ID\tEmployee Name\tDepartment\tAttendance Days\tLate Days\tEarly Leave Days\tLeave Days\n");

    for(int i = 0; i < system->employeeCount; i++) {
        int attendanceDays = 0;
        int lateDays = 0;
        int earlyLeaveDays = 0;
        int leaveDays = 0;

        for(int j = 0; j < system->recordCount; j++) {
            if(system->records[j].employeeId == system->employees[i].id &&
               strcmp(system->records[j].date, startDate) >= 0 &&
               strcmp(system->records[j].date, endDate) <= 0) {

                if(system->records[j].leaveType > 0) {
                    leaveDays++;
                } else if(strcmp(system->records[j].checkIn, "00:00") != 0 &&
                          strcmp(system->records[j].checkOut, "00:00") != 0) {
                    attendanceDays++;

                    // Simple late check (assume late if after 9:00)
                    if(strcmp(system->records[j].checkIn, "09:00") > 0) {
                        lateDays++;
                    }

                    // Simple early leave check (assume early if before 17:00)
                    if(strcmp(system->records[j].checkOut, "17:00") < 0) {
                        earlyLeaveDays++;
                    }
                }
            }
        }

        printf("%d\t%s\t\t%s\t\t%d\t\t%d\t\t%d\t\t%d\n", 
               system->employees[i].id,
               system->employees[i].name,
               system->employees[i].department,
               attendanceDays,
               lateDays,
               earlyLeaveDays,
               leaveDays);
    }
}

// Save data to file
void saveData(AttendanceSystem* system) {
    FILE* empFile = fopen("employees.dat", "wb");
    FILE* recFile = fopen("records.dat", "wb");

    if(empFile) {
        fwrite(&system->employeeCount, sizeof(int), 1, empFile);
        fwrite(system->employees, sizeof(Employee), system->employeeCount, empFile);
        fclose(empFile);
    }

    if(recFile) {
        fwrite(&system->recordCount, sizeof(int), 1, recFile);
        fwrite(system->records, sizeof(AttendanceRecord), system->recordCount, recFile);
        fclose(recFile);
    }

    printf("Data has been saved!\n");
}

// Load data from file
void loadData(AttendanceSystem* system) {
    FILE* empFile = fopen("employees.dat", "rb");
    FILE* recFile = fopen("records.dat", "rb");

    if(empFile) {
        fread(&system->employeeCount, sizeof(int), 1, empFile);
        fread(system->employees, sizeof(Employee), system->employeeCount, empFile);
        fclose(empFile);
    }

    if(recFile) {
        fread(&system->recordCount, sizeof(int), 1, recFile);
        fread(system->records, sizeof(AttendanceRecord), system->recordCount, recFile);
        fclose(recFile);
    }
}

// Find employee by ID
int findEmployeeById(AttendanceSystem* system, int id) {
    for(int i = 0; i < system->employeeCount; i++) {
        if(system->employees[i].id == id) {
            return i;
        }
    }
    return -1;
}

// Find attendance record
int findRecord(AttendanceSystem* system, int employeeId, const char* date) {
    for(int i = 0; i < system->recordCount; i++) {
        if(system->records[i].employeeId == employeeId && 
           strcmp(system->records[i].date, date) == 0) {
            return i;
        }
    }
    return -1;
}

// Get current date
void getCurrentDate(char* date) {
    time_t t = time(NULL);
    struct tm tm = *localtime(&t);
    sprintf(date, "%04d-%02d-%02d", tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday);
}

// Get current time
void getCurrentTime(char* ctime) {
    time_t t = time(NULL);
    struct tm tm = *localtime(&t);
    sprintf(ctime, "%02d:%02d", tm.tm_hour, tm.tm_min);
}

Testing

Complete Source Code | C Language Design and Implementation of Employee Attendance System
image
D:\CODING\cyyzwsq\EmployeeSM\cmake-build-debug\EmployeeSM.exe
Welcome to the Employee Attendance Management System!

===== Employee Attendance Management System =====
1. Add Employee
2. Check-in
3. Check-out
4. Leave
5. Query Attendance Records
6. Generate Attendance Report
0. Exit System
============================
Please select an operation:1

Please enter employee ID:1001

Please enter employee name:Zhang San

Please enter employee department:IT

Employee added successfully!

===== Employee Attendance Management System =====
1. Add Employee
2. Check-in
3. Check-out
4. Leave
5. Query Attendance Records
6. Generate Attendance Report
0. Exit System
============================
Please select an operation:1

Please enter employee ID:1002

Please enter employee name:Li Si

Please enter employee department:Sales

Employee added successfully!

===== Employee Attendance Management System =====
1. Add Employee
2. Check-in
3. Check-out
4. Leave
5. Query Attendance Records
6. Generate Attendance Report
0. Exit System
============================
Please select an operation:5

Please enter employee ID:1001

Please enter start date (YYYY-MM-DD):2025-08-01

Please enter end date (YYYY-MM-DD):2025-09-08


Zhang San's attendance records (2025-08-01 to 2025-09-08):
Date		Check-in Time	Check-out Time	Leave Type	Remarks
No attendance records for this time period!

===== Employee Attendance Management System =====
1. Add Employee
2. Check-in
3. Check-out
4. Leave
5. Query Attendance Records
6. Generate Attendance Report
0. Exit System
============================
Please select an operation:2

Please enter employee ID:1001

Check-in successful! Time: 2025-09-08 20:56

===== Employee Attendance Management System =====
1. Add Employee
2. Check-in
3. Check-out
4. Leave
5. Query Attendance Records
6. Generate Attendance Report
0. Exit System
============================
Please select an operation:2

Please enter employee ID:1002

Check-in successful! Time: 2025-09-08 20:56

===== Employee Attendance Management System =====
1. Add Employee
2. Check-in
3. Check-out
4. Leave
5. Query Attendance Records
6. Generate Attendance Report
0. Exit System
============================
Please select an operation:6

Please enter start date (YYYY-MM-DD):2025-09-01

Please enter end date (YYYY-MM-DD):2025-09-08


Attendance Report (2025-09-01 to 2025-09-08):
Employee ID	Employee Name	Department	Attendance Days	Late Days	Early Leave Days	Leave Days
1001	Zhang San		IT		0		0		0		0
1002	Li Si		Sales		0		0		0		0

===== Employee Attendance Management System =====
1. Add Employee
2. Check-in
3. Check-out
4. Leave
5. Query Attendance Records
6. Generate Attendance Report
0. Exit System
============================
Please select an operation:3

Please enter employee ID:1001

Check-out successful! Time: 2025-09-08 20:58

===== Employee Attendance Management System =====
1. Add Employee
2. Check-in
3. Check-out
4. Leave
5. Query Attendance Records
6. Generate Attendance Report
0. Exit System
============================
Please select an operation:3

Please enter employee ID:1002

Check-out successful! Time: 2025-09-08 20:58

===== Employee Attendance Management System =====
1. Add Employee
2. Check-in
3. Check-out
4. Leave
5. Query Attendance Records
6. Generate Attendance Report
0. Exit System
============================
Please select an operation:6

Please enter start date (YYYY-MM-DD):2025-09-01

Please enter end date (YYYY-MM-DD):2025-09-08


Attendance Report (2025-09-01 to 2025-09-08):
Employee ID	Employee Name	Department	Attendance Days	Late Days	Early Leave Days	Leave Days
1001	Zhang San		IT		1		1		0		0
1002	Li Si		Sales		1		1		0		0

===== Employee Attendance Management System =====
1. Add Employee
2. Check-in
3. Check-out
4. Leave
5. Query Attendance Records
6. Generate Attendance Report
0. Exit System
============================
Please select an operation:4

Please enter employee ID:1001

Please enter leave date (YYYY-MM-DD):2025-09-08

Please select leave type (1. Personal Leave 2. Sick Leave 3. Annual Leave):3

Please enter leave reason:Urgent matter

Leave application submitted successfully!

===== Employee Attendance Management System =====
1. Add Employee
2. Check-in
3. Check-out
4. Leave
5. Query Attendance Records
6. Generate Attendance Report
0. Exit System
============================
Please select an operation:6

Please enter start date (YYYY-MM-DD):2025-09-01

Please enter end date (YYYY-MM-DD):2025-09-08


Attendance Report (2025-09-01 to 2025-09-08):
Employee ID	Employee Name	Department	Attendance Days	Late Days	Early Leave Days	Leave Days
1001	Zhang San		IT		0		0		0		1
1002	Li Si		Sales		1		1		0		0

===== Employee Attendance Management System =====
1. Add Employee
2. Check-in
3. Check-out
4. Leave
5. Query Attendance Records
6. Generate Attendance Report
0. Exit System
============================
Please select an operation:5

Please enter employee ID:1001

Please enter start date (YYYY-MM-DD):2025-09-01

Please enter end date (YYYY-MM-DD):2025-09-08


Zhang San's attendance records (2025-09-01 to 2025-09-08):
Date		Check-in Time	Check-out Time	Leave Type	Remarks
2025-09-08	20:56		20:58		Annual Leave	Urgent matter

===== Employee Attendance Management System =====
1. Add Employee
2. Check-in
3. Check-out
4. Leave
5. Query Attendance Records
6. Generate Attendance Report
0. Exit System
============================
Please select an operation:

Extension Suggestions

  1. A permission management system can be added to distinguish between administrators and regular employees
  2. More complex attendance rules can be added, such as flexible working hours, overtime calculations, etc.
  3. A data export function can be added to support exporting reports in Excel or PDF format
  4. Network functionality can be added to implement multi-terminal attendance records

This system provides basic attendance management functions and can be further expanded and optimized according to actual needs.

--End--

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