C庫函數(shù) void isalnum(int c)檢查,傳遞的字符字母是否為數(shù)字。
以下是isalnum()函數(shù)的聲明。
int isalnum(int c);
c -- 這是要檢查的字符。
這個函數(shù)返回非零值,如果c是一個數(shù)字或字母,否則為0
下面的例子顯示isalnum()函數(shù)的用法。
#include <stdio.h> #include <ctype.h> int main() { int var1 = 'd'; int var2 = '2'; int var3 = ' '; int var4 = ' '; if( isalnum(var1) ) { printf("var1 = |%c| is alphanumeric ", var1 ); } else { printf("var1 = |%c| is not alphanumeric ", var1 ); } if( isalnum(var2) ) { printf("var2 = |%c| is alphanumeric ", var2 ); } else { printf("var2 = |%c| is not alphanumeric ", var2 ); } if( isalnum(var3) ) { printf("var3 = |%c| is alphanumeric ", var3 ); } else { printf("var3 = |%c| is not alphanumeric ", var3 ); } if( isalnum(var4) ) { printf("var4 = |%c| is alphanumeric ", var4 ); } else { printf("var4 = |%c| is not alphanumeric ", var4 ); } return(0); }
讓我們編譯和運(yùn)行上面的程序,這將產(chǎn)生以下結(jié)果:
var1 = |d| is alphanumeric var2 = |2| is alphanumeric var3 = | | is not alphanumeric var4 = | | is not alphanumeric