C库函数 - isupper() C库函数 - isspace() C库函数 - isxdigit() C库函数 - isupper() #include <stdio.h> #include <ctype.h> int main () { int var1 = 'M'; int var2 = 'm'; int var3 = '3'; if( isupper(var1) ) { printf("var1 = |%c| is uppercase character\n", var1 ); } else { printf("var1 = |%c| is not uppercase character\n", var1 ); } if( isupper(var2) ) { printf("var2 = |%c| is uppercase character\n", var2 ); } else { printf("var2 = |%c| is not uppercase character\n", var2 ); } if( isupper(var3) ) { printf("var3 = |%c| is uppercase character\n", var3 ); } else { printf("var3 = |%c| is not uppercase character\n", var3 ); } return(0); } C库函数 - isspace() C库函数 - isxdigit()