增量和减量运算符 [英] Increment and Decrement Operators

问题描述

#include <stdio.h>

int main()
{
  int x = 4, y, z;
  y = --x;
  z = x--;
  printf("%d %d %d", x, y, z);
}

输出:2 3 3

有人可以解释吗?
i =+ j是什么意思(假设i = 1和j = 2)?

解决方案

简单说明:

-x或++ x :之后将修改值.

x--或x ++ :值将在之前修改

详细说明:

-x或++ x :预减量/增量:首先将进行减量或增量操作，然后将x赋值.

x--或x ++ : post:减量/增量:将首先分配x的值，然后再进行减量或增量操作.

让我们以更好的格式编写代码，并逐步检查代码并对其进行注释，以直观地向您展示发生的情况:

main() {
    //We declare the variables x, y and z, only x is given a value of 4.
    int x=4,y,z;

    //--x will decrement var x by 1 first THEN it will assign the value of x to y.
    //so: x = 3, y = 3 and z = nothing yet.
    y = --x;

    //x-- will assign the value of x to z first, then var x will be decremented by 1 after.
    //so: x = 2, y=3 and z = 3
    z = x--; 

    printf ("\n %d %d %d", x,y,z);

}

#include <stdio.h>

int main()
{
  int x = 4, y, z;
  y = --x;
  z = x--;
  printf("%d %d %d", x, y, z);
}

Output: 2 3 3

Can anyone explain this?
And what does i =+ j mean (suppose i = 1 and j = 2)?

解决方案

simple explanation:

--x or ++x : Value will be modified after.

x-- or x++ : Value will be modified before

Detailed explanation:

--x or ++x: pre-decrement/increment: will first do the operation of decrementing or incrementing first, then it will assign x.

x-- or x++: post:decrement/increment: will first assign the value of x and then it will do the operation of decrementing or incrementing after.

lets write your code in a nicer format and go through your code step by step and annotate it to show you visually what happens:

main() {
    //We declare the variables x, y and z, only x is given a value of 4.
    int x=4,y,z;

    //--x will decrement var x by 1 first THEN it will assign the value of x to y.
    //so: x = 3, y = 3 and z = nothing yet.
    y = --x;

    //x-- will assign the value of x to z first, then var x will be decremented by 1 after.
    //so: x = 2, y=3 and z = 3
    z = x--; 

    printf ("\n %d %d %d", x,y,z);

}

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