c++ transform用法 大小写转换

一、

void f7(){
    string s1="AAAbbb";
    transform(s1.begin(),s1.end(),s1.begin(),toupper);
    cout<<"全部转化为大写："<<s1<<endl;
    transform(s1.begin(),s1.end(),s1.begin(),tolower);
    cout<<"全部转化为小写："<<s1<<endl;
}

结果：全部转化为大写：AAABBB; 
全部转化为小写：aaabbb;

二、 

#include <iostream>
#include <algorithm>
using namespace std;
char op(char ch)
{
 
   if(ch>='A'&&ch<='Z')
        return ch+32;
    else
        return ch;
}
int main()
{
    string first,second;
    cin>>first;
    second.resize(first.size());
    transform(first.begin(),first.end(),second.begin(),op);
    cout<<second<<endl;
    return 0;
}

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https://blog.youkuaiyun.com/sun223173/article/details/80631252

https://blog.youkuaiyun.com/fyf18845165207/article/details/82729859