The difference between x++ and ++x in c language

The difference between x and When x is used as the left operand, the result is the same, but when used as the right operand, the result may be different due to differences in execution order.

The difference between x and x in C language

x and x are both used for auto-increment in C language operators for the variable x, but they have subtle differences in the order of execution, resulting in different results.

x (post-increment) :

• First perform an arithmetic operation on variable x, and then assign the result back to x. The
• operator is placed after the variable x.

Operator is placed before variable x.

• Difference in execution order
:

x:

Save the value of x to a temporary variable, and then It performs an increment operation and finally assigns the result back to x.

• x: Directly add 1 to the value of x, and then perform arithmetic operations.
• Difference in results
:

In an expressionusing x as the left operand, x and x have the same result because The addition occurs before the expression is evaluated. For example:

<code class="c">int x = 5;
printf("x = %d\n", x++); // 输出5
printf("x = %d\n", ++x); // 输出7</code>

But in an expressionusing x as the right operand, the results of x and x are different.

Example 1:

<code class="c">int y = 5;
z = x++ + y; // z = 11</code>

Post-increment x. First assign the value 5 of x to z, and then add 1 to x to become 6. Therefore, z = 5 6 = 11.

• Example 2:

<code class="c">int y = 5;
z = ++x + y; // z = 12</code>

Prefixed auto-increment x first adds 1 to x to become 6, and then assigns 6 to z. Therefore, z = 6 5 = 12.

• Summary:

x (post-increment) performs arithmetic operations first and then assigns values.

x (prefixed auto-increment) is assigned a value first, and then performs arithmetic operations.

• When using x as the left operand, the results of x and x are the same.
• When using x as the right operand, the results of x and x may be different, depending on the order of execution.

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