What do the two equal signs in C language mean?

The double equal sign (==) is a comparison operator, used to compare whether the values ​​​​of two expressions are equal and return a Boolean value (true/false). Uses include: comparing variable values, determining whether an expression is true, checking conditional statements and loop termination conditions. It should be noted that the double equal sign can only compare expressions of the same type, and is different from the assignment operator (=).

Double equal sign in C language

In C language, the double equal sign (==) is Comparison operators are used to compare whether the values ​​of two expressions are equal. It returns a boolean value that is true if the expressions are equal, false otherwise.

Purpose

The double equal sign is usually used in the following situations:

• Compares whether the values ​​​​of two variables are equal
• Determine whether the expression is true
• Check the condition in the conditional statement
• Check the termination condition in the loop

Syntax

The syntax of the double equal sign operator is as follows:

<code>expr1 == expr2</code>

where:

• expr1 and expr2 are the two to be compared Expressions

Examples

The following are some examples of the double equal sign operator:

int x = 5;
int y = 5;

if (x == y) {
  printf("x 和 y 相等\n");
}

if (x == 10) {
  printf("x 等于 10\n"); // 不会执行，因为 x 不等于 10
}

Note

• Double equal signs can only compare expressions of the same type.
• The double equal sign is different from the assignment operator (=), which is used to assign a value to a variable.

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