C库函数 - isxdigit() C库函数 - isupper() C库函数 - tolower() C库函数 - isxdigit() #include <stdio.h> #include <ctype.h> int main () { char var1[] = "tuts"; char var2[] = "0xE"; if( isxdigit(var1[0]) ) { printf("var1 = |%s| is hexadecimal character\n", var1 ); } else { printf("var1 = |%s| is not hexadecimal character\n", var1 ); } if( isxdigit(var2[0] )) { printf("var2 = |%s| is hexadecimal character\n", var2 ); } else { printf("var2 = |%s| is not hexadecimal character\n", var2 ); } return(0); } C库函数 - isupper() C库函数 - tolower()