调用函数:
tolower( ) //大写字母转换成小写字母
toupper( ) //小写字母转换成大写字母
#include#include using namespace std; int main() { string str= "THIS IS A STRING"; for (int i=0; i

#include#include using namespace std; int main() { string str= "THIS IS A STRING"; for (int i=0; i