include #include void main(){char ch=’A’;ch=tolower(ch);printf(“%c”,ch);include #include void main(){char ch=’A’;ch=tolower(ch);printf(“%c”,ch);ch=’b’;ch=toupper(ch);printf(“%c”,ch);} ch=a;ch=B tolower函数将大写转换为小写toupper函数将小写转换为大写在前加#include