linux下c语言环境变量操作的几个相关函数

最新推荐文章于 2018-12-24 15:52:00 发布

原创最新推荐文章于 2018-12-24 15:52:00 发布 · 835 阅读

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本文深入解析了C语言中用于环境变量操作的四个关键函数:getenv、putenv、setenv、unsetenv。详细介绍了每个函数的用法、参数以及返回值，帮助开发者熟练掌握环境变量管理技巧。

这几个函数的原型在<stdio.h>中定义

/* Return the value of envariable NAME, or NULL if it doesn't exist. */
extern char *getenv (__const char *__name) __THROW __nonnull ((1)) __wur;

/* The SVID says this is in <stdio.h>, but this seems a better place.   */
/* Put STRING, which is of the form "NAME=VALUE", in the environment.
   If there is no `=', remove NAME from the environment. */
extern int putenv (char *__string) __THROW __nonnull ((1));

/* Set NAME to VALUE in the environment.
   If REPLACE is nonzero, overwrite an existing value. */
extern int setenv (__const char *__name, __const char *__value, int __replace)
     __THROW __nonnull ((2));

/* Remove the variable NAME from the environment. */
extern int unsetenv (__const char *__name) __THROW __nonnull ((1));