string conversion case (C + +)

How do I convert a string to uppercase or lowercase? This is something that often needs to be done in string matching, but the standard library of C + + does not provide the ability to turn std::string into uppercase and lowercase, only to provide the ability to turn char into uppercase (toupper) and lowercase (tolower).
But we can use the STL transform with Toupper/tolower, complete std::string conversion Large (small) write function, also see the power of template programming, a transform function, can be applied to any type, and as long as they provide functions, You can complete any transform action.

C++

#include <iostream> #include <string> #include <cctype> #include <algorithm>using namespace std ; int main () {    string s = "Clare";    ToUpper    Transform (S.begin (), S.end (), S.begin (),:: ToUpper);    ToLower    //transform (S.begin (), S.end (), S.begin (),:: ToLower);    cout << s << endl;}

C

#include <stdio.h> #include <ctype.h>int main () {    char s[] = "Clare";    int i =-1;    while (s[i++])         s[i] = ToUpper (S[i]);    S[i] = ToLower (S[i]);    Puts (s);  }

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String Conversion case (c + +)