โ๏ธ Detailed Explanation of C Language Operators and Expressions โ Comprehensive Understanding of Arithmetic, Logical, and Assignment Operators
๐งฉ I. Introduction
In the previous section, we learned about variable definitions and input/output functions (printf, scanf). However, the true “soul” of a program lies in its ability to perform calculations and logical judgments on data. In this lesson, we will comprehensively master the operators and expressions in C language โ enabling your program to not only “display” but also “think”!
๐งฎ II. What are Operators and Expressions
โ Operator
An operator is a symbol that performs operations on variables or constants. For example: +, -, *, /, %, ==, &&, etc.
โ Expression
An expression is a combination of operators and operands that results in a value after evaluation. For example:
a + b x * y – 3 (a + b) * c
โ III. Arithmetic Operators
Arithmetic operators are used for mathematical calculations and are the most common type of operations.
Operator Meaning Example Result
- Add 3 + 2 5
- Subtract 5 – 2 3
- Multiply 4 * 3 12 / Divide 7 / 2 3 (integer division truncates)
- Modulo 7 % 2 1
๐ง Note:
-
If both numbers are integers, the result of / will be an integer.
-
To obtain a decimal result, use floating-point types:
float result = 7.0 / 2; printf(“%.2f”, result); // Output 3.50
โ๏ธ IV. Relational Operators
Used to compare the size relationship between two values, the result can only be two types: ๐ True (1) or False (0).
Operator Meaning Example Result
== Equal a == b True if equal != Not equal a != b True if not equal
Greater than a > b True if a is greater < Less than a < b True if a is less = Greater than or equal a >= b True if condition is met <= Less than or equal a <= b True if condition is met
โ Example:
int a = 5, b = 8; printf(“%d\n”, a > b); // Output 0 (false) printf(“%d\n”, a != b); // Output 1 (true)
๐งฉ V. Logical Operators
Logical operators are used to combine multiple conditions, commonly used in if statements.
Operator Meaning Example Result
&& And (&&) a > 0 && b > 0 True if both conditions are true Or (||) ! Not !(a > b) Negation, true becomes false, false becomes true
โ Example:
int a = 10, b = 20; if (a > 0 && b > 0) { printf(“a and b are both positive\n”); }
๐ VI. Assignment Operators
Operator Meaning Example Equivalent to
= Assignment a = 5 โ += Add and assign a += 3 a = a + 3 -= Subtract and assign a -= 2 a = a – 2 *= Multiply and assign a *= 2 a = a * 2 /= Divide and assign a /= 2 a = a / 2 %= Modulo and assign a %= 3 a = a % 3
โ Example:
int a = 10; a += 5; // Equivalent to a = a + 5 printf(“%d\n”, a); // Output 15
๐งฎ VII. Increment and Decrement Operators
Operator Meaning Example Description
++ Increment by 1 a++ or ++a Variable increases by 1 — Decrement by 1 a– or –a Variable decreases by 1
โ ๏ธ Difference:
int a = 5; printf(“%d\n”, a++); // Use first then add โ Output 5 printf(“%d\n”, ++a); // Add first then use โ Output 7
โ๏ธ VIII. Comprehensive Case: Finding the Maximum of Three Numbers
#include <stdio.h> int main() { int a, b, c, max; printf("Please enter three integers:"); scanf("%d %d %d", &a, &b, &c); max = a; // Assume a is the largest if (b > max) max = b; // Compare b if (c > max) max = c; // Compare c printf("The maximum value is: %d\n", max); return 0; }Example of running result:
Please enter three integers: 8 3 9 The maximum value is: 9
๐ง IX. Class Summary
โ In this section, we have mastered:
The classification and usage of various operators in C language
The basic logic of expression evaluation
The role of relational and logical operators in conditional statements
The simplified syntax for assignment, increment, and decrement
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