The difference between single equal sign and double equal sign in C language

The single equal sign (=) is used for assignment, assigning the right value to the left variable; the double equal sign (==) is used for comparison, to determine whether the two operands are equal, and return 0 (false) or 1 (real).

The difference between single equal sign and double equal sign in C language

In C language, single equal sign (=) and the double equal sign (==) have different usages:

Single equal sign (=)

• Assignment operator: is used to assign the value on the right to the variable or memory address on the left.

Double equal sign (==)

• ##Comparison operator: is used for comparison Whether the values ​​of the two operands are equal.
The comparison type can be integer, floating point number or string.

Specific differences

FeaturesSingle equal sign (Double equal sign (##UsageOperation resultReturn Value

	= )	==)
Assignment	Comparison
The left operand is assigned the right value	The return value indicates whether the two operands are equal (true or False)
None	0 (False) or 1 (True)

Example

int x = 10; // 赋值
if (x == 10) { // 比较
    // 代码块
}

Note:

The single equal sign cannot be used interchangeably with the double equal sign.

• Since the assignment operator has a higher priority than the comparison operator, when used in an expression, the assignment operator is executed first.
• When comparing strings, the double equal sign (
==
• ) only compares the address of the string, not the string content. To compare string contents, use the strcmp() function.

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