In C51 microcontroller development, the C language is an essential skill, and operators are the core part of C language—they manipulate data, optimize hardware operations, and can even directly affect program efficiency!
Today, we bring you a comprehensive guide to C51 operators, teaching you to master these key knowledge points step by step. This article covers 8 core operators and 20 practical cases to help you progress from “basic usage” to “proficiency”!
1. Arithmetic Operators
Arithmetic operators are used for basic mathematical operations, including addition, subtraction, multiplication, division, and
Example:
int a = 10, b = 3;
a + b; // 13 → Addition
a – b; // 7 → Subtraction
a * b; // 30 → Multiplication
a / b; // 3 → Division (integer part)
a % b; // 1 → Modulus (remainder)
2. Logical Operators
Logical operators are used for Boolean logic operations, including logical AND, logical OR, and logical NOT.
1) Logical AND: &&, the result is true if both operands are true; otherwise, it is false.
2) Logical OR: ||, the result is true if at least one operand is true; it is false if both are false.
3) Logical NOT: !, the result is false if the operand is true; it is true if the operand is false.
Example:
int f = (5 > 3) && (2 < 4); // f = 1 (true)
int g = (5 < 3) || (2 < 4); // g = 1 (true)
int h = !(5 < 3); // h = 1 (true)
3. Relational Operators
Relational operators are used in conditional statements to compare two values. When the relationship is satisfied, the result is true; when not satisfied, the result is false, returning a Boolean value. The types include the following four:
Greater than: >
Less than: <
Equal to: ==
Not equal to: !=
int i = (5 > 3); // i = 1 (true)
int j = (5 < 3); // j = 0 (false)
int k = (5 == 5); // k = 1 (true)
int l = (5 != 3); // l = 1 (true)
4. Bitwise Operators
Bitwise operators are used to directly manipulate binary bits, commonly used in microcontroller development to handle binary issues. The types include the following six:
Bitwise AND: &
Bitwise OR: |
Bitwise XOR: ^
Bitwise NOT: ~
Left shift: <<
Right shift: >>
int m = 5 & 3; // m = 1 (binary: 101 & 011 = 001)
int n = 5 | 3; // n = 7 (binary: 101 | 011 = 111)
int o = 5 ^ 3; // o = 6 (binary: 101 ^ 011 = 110)
int p = ~5; // p = -6 (binary: ~101 = 010, two’s complement representation)
int q = 5 << 1; // q = 10 (binary: 101 << 1 = 1010)
int r = 5 >> 1; // r = 2 (binary: 101 >> 1 = 010)
5. Compound Assignment Operators
Compound assignment operators are used to simplify assignment operations, with a total of 10 types.
The general format for using compound operators is: “variable compound operator expression”. The process involves first performing the operation between the variable and the expression, then assigning the result to the variable.
Add assignment: +=
Subtract assignment: -=
Multiply assignment: *=
Divide assignment: /=
Modulus assignment: %=
Bitwise AND assignment: &=
Bitwise OR assignment: |=
Bitwise XOR assignment: ^=
Left shift assignment: <=
Right shift assignment: >=
int s = 5;
s += 3; // equivalent to s=(s+3), s = 8
int t = 5;
t -= 3; // equivalent to t=(t-3), t = 2
int u = 5;
u *= 3; // equivalent to u=(u*3), u = 15
int v = 5;
v /= 3; // equivalent to v=(v/3), v = 1
6. Comma Operator
The comma operator is a special operator with the lowest precedence, used to combine multiple expressions, returning the value of the last expression.
int x = (a = 3, b = 4, a + b); // x = 7
7. Conditional Operator
The conditional operator is the only ternary operator in C language, used for ternary expressions, with three operands that return different values based on the condition.
The general form of a conditional expression is as follows:
Logical expression ? Expression1 : Expression2
int y = (5 > 3) ? 10 : 20; // y = 10
8. Pointer Address Operators
C51 provides two special pointer and address operators for manipulating memory addresses.
Address of: &
int z = 5;
int *ptr = &z; // ptr points to the address of z
Dereference (get value): *
int value = *ptr; // value = 5
C51 operators are the foundation of microcontroller programming. Mastering these operators can make your code more concise and efficient. We have detailed arithmetic operators, logical operators, relational operators, bitwise operators, compound assignment operators, comma operators, conditional operators, and pointer address operators, along with examples to help everyone better understand.
Get started and try it out! If you encounter any issues during your learning process, feel free to leave a comment, and I will respond promptly. If you find this useful, remember to like and follow! See you next time!
●Study Notes No.5: “The Language of Microcontrollers”: Assembly Language and C Language
● Study Notes No.4: “The Hands and Feet of Microcontrollers”: Detailed Explanation of I/O Ports
● Study Notes No.3: “The Brain of Microcontrollers”: The Role of Memory
● Study Notes Day 2: “The Heart of Microcontrollers”: CPU Architecture
● Study Notes Day 1: “Starting the Exploration Journey for Microcontroller Beginners”
