[c/c++] programming之路（8）、汇编、求模、自增自减

一、插入汇编

#include<stdio.h> 

void main(){
    int num=10;
    num=num+5;
    //插入汇编语言
    _asm{
        mov eax,num;//eax是一个存储器，将num的值移动到eax
        add eax,5    //eax值+5
        mov num,eax    //eax值赋给num
    }
    printf("%d",num);
    getchar();
}

二、求模运算，颠覆数

#include<stdio.h> 
#include<stdlib.h> 

void main1(){
    //int num=5%9.0;//报错，求模运算只能是整数
    //int num='A'%3;//65%3=2
    printf("%d",3%5);//3=0*5+3
    printf("
%d",5%3);//5=1*3+2
    printf("
%d",3%-5);//3=1*-5+3
    printf("
%d",-3%-5);//-3=0*-5-3
    printf("
%d",-3%5);//-3=0*5-3
    printf("
%d",5%-3);//5=-1*-3+2
    getchar();
}
//面试题：不准用求模运算
/*
    120%19->6=120-120/19*19
    100%40->20=100-100/40*40
    x%y=x-x/y*y
*/
void main2(){
    int x,y;
    scanf("%d%d",&x,&y);
    printf("x=%d,y=%d",x,y);
    //printf("
%d",x%y);
    printf("
%d",x-x/y*y);

    system("pause");
}
//颠覆数    123->321    456->654
void main(){
    int num,ge,shi,bai;
    scanf("%d",&num);

    ge=num%10;
    shi=num/10%10;
    bai=num/100;

    printf("%d",ge*100+shi*10+bai);
    system("pause");
}

练习：四位数颠覆，不允许使用求模运算

#include<stdio.h> 
#include<stdlib.h> 
void main(){
    int num,ge,shi,bai,qian;
    scanf("%d",&num);

    ge=num-num/10*10;
    shi=num/10-num/100*10;
    bai=num/100-num/1000*10;
    qian=num/1000;

    printf("%d",ge*1000+shi*100+bai*10+qian);
    system("pause");
}

三、自增自减

#include<stdio.h> 
#include<stdlib.h> 

void main2(){
    //++--高于乘除，乘除高于+-
    int num=3;
    printf("%d",-num++);//-3
    printf("
%d",num);//4
    system("pause");
}
void main(){
    int a=3;
    int b=4;
    int num=10;
    printf("%d",a+++b);//->(a++)+b
    printf("
%d",a);//4

    //printf("
%d",(10*num)++);//报错，“++”需要左值（表达式不能用++--）
    printf("
%d",10*num++);//100
    system("pause");
}