c# 小程序支付后台示例

The #if is a preprocessor directive in C programming language and it is used for conditional compilation.

#if是C编程语言中的预处理程序指令，用于条件编译。

General for of the #if directive is:

#if指令的常规为：

    #if conditional_expression 
statements;
#endif

If conditional_expression is true, the code written between #if and #endif i.e. the statements will be executed.

如果conditional_expression为true，则将执行在#if和#endif之间编写的代码，即语句 。

Example:

例：

#include <stdio.h>
#define MAX_GF 100
int main(){
printf("Hello\n");
#if MAX_GF>=50
printf("Wau, you may have more than 50 girlfriends\n");
printf("Code for more than 50 GFs\n");
#endif
printf("Bye!\n");
return 0;
}

Output

输出量

    Hello
Wau, you may have more than 50 girlfriends
Code for more than 50 GFs
Bye!

翻译自: https://www.includehelp.com/c-programs/if-directive-example.aspx

c# 小程序支付后台示例