编辑代码

#include <stdio.h>

int a=0;
int main () {
    void momo();
    int x;

    x=0;
    momo(x);
    printf("%d\n",a);
    
    x=1;
    momo(x);
    printf("%d\n",a);

    x=2;
    momo(x);
    printf("%d\n",a);

    x=3;
    momo(x);
    printf("%d\n",a);
}
void momo(int x){
    switch(x){
        case 1:
            a+=1;
        case 2:
            a+=2;
            break;
        case 3:
            a+=3;
            break;
        default:
            a=4;
    }
}