二十五岁时我们都一样愚蠢、多愁善感，喜欢故弄玄虚，可如果不那样的话，五十岁时也就不会如此明智。
标题：C库函数 isalnum()
C库函数 isalnum()
#include <stdio.h> #include <ctype.h> int main () { int var1 = 'd'; int var2 = '2'; int var3 = '\t'; int var4 = ' '; if( isalnum(var1) ) { printf("var1 = |%c| is alphanumeric\n", var1 ); } else { printf("var1 = |%c| is not alphanumeric\n", var1 ); } if( isalnum(var2) ) { printf("var2 = |%c| is alphanumeric\n", var2 ); } else { printf("var2 = |%c| is not alphanumeric\n", var2 ); } if( isalnum(var3) ) { printf("var3 = |%c| is alphanumeric\n", var3 ); } else { printf("var3 = |%c| is not alphanumeric\n", var3 ); } if( isalnum(var4) ) { printf("var4 = |%c| is alphanumeric\n", var4 ); } else { printf("var4 = |%c| is not alphanumeric\n", var4 ); } return(0); }
