易错程序分析题 C++（dating)

Posted 2021-06-03 犬饲Atsuhiro

本文仅整理C++中易错（不一定难）的题目，有疑问欢迎私聊。题目的答案需要使用编译器运行后自行对照，不便之处，敬请谅解。程序已经测试可以运行。

注意每题都有坑，认真分析。

#include <bits/stdc++.h>
using namespace std;
main()
{
    int a=12;
    a+=a-=a*a;
    cout<<a<<endl;
    return 0;
 } 

 

#include <bits/stdc++.h>
using namespace std;
main()
{
    int i,x=4,y=5;
    i=++x==5||++y==6;
    cout<<"x="<<x<<endl<<"y="<<y<<endl<<"i="<<i<<endl;
    return 0; 
 } 

 

#include <bits/stdc++.h>
using namespace std;
main()
{
    int i,x=4,y=5;
    i=x++==5&&y++==6;
    cout<<"x="<<x<<endl<<"y="<<y<<endl<<"i="<<i<<endl;
    return 0; 
 } 

 

#include <bits/stdc++.h>
using namespace std;
main()
{
    int x=1,y=2,z=3;
    x+=y+=z;
    cout<<(x<y?y:x)<<endl;
    cout<<(x<y?x++:y++)<<endl;
    cout<<x<<","<<y<<endl;
    cout<<(z+=x>y?x++:y++)<<endl;
    cout<<y<<","<<z<<endl;
    x=3;y=z=4;
    cout<<(z>y&&y==x?1:0)<<endl;
    cout<<(z>=y&&y>=x)<<endl;
    return 0;
 } 

 

本题输入为2473

#include <bits/stdc++.h>
using namespace std;
main()
{
    char ch;
    while(cin.get(ch)&&ch!=\'\\n\')
    switch(ch-\'2\')
        {case 0:
         case 1:cout<<(char)(ch+4);
         case 2:cout<<(char)(ch+4);break;
         case 3:cout<<(char)(ch+3);
         default:cout<<(char)(ch+2);break;
        }
    cout<<endl;
    return 0;
 } 

 

#include <bits/stdc++.h>
using namespace std;
main()
{
    int a=10,y=0;
    do
    {
        a+=2;y+=a;
        cout<<"a="<<a<<",y="<<y<<endl;
        if(y>50) break;
    }
    while(a=14);
    return 0;
 } 

 

#include <bits/stdc++.h>
using namespace std;
main()
{
    int i;
    for (i=1;i<=5;i++)
        {
            if(i%2) cout<<"*";
            else continue;
            cout<<"#";
        }
        cout<<"$\\n";
        return 0;
 } 

 

#include <bits/stdc++.h>
using namespace std;
main()
{
    int k=0;char c=\'A\';
    do
    {switch(c++)
        {case\'A\':k++;break;
         case\'B\':k--;
         case\'C\':k+=2;break;
         case\'D\':k=k%2;continue;
         case\'E\':k=k*10;break;
         default:k=k/3;
         } 
    k++;
    }while(c<\'G\');
    cout<<"k="<<k<<endl;
    return 0; 
 } 

 

#include <bits/stdc++.h>
using namespace std;
void fun (int x,int y)
{
    x=x*10;
    y=y+x;
    cout<<x<<\'\\t\'<<y<<endl;
}

main()
{
    int a=2,b=3;
    fun(a+b,a*b);
    cout<<a<<\'\\t\'<<b<<endl;
    return 0;
}