std::getenv
| Defined in header <cstdlib>
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| char* getenv( const char* env_var ); |
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Searches the environment list provided by the host environment (the OS), for a string that matches the C string pointed to by env_var and returns a pointer to the C string that is associated with the matched environment list member.
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This function is not required to be thread-safe. Another call to |
(until C++11) |
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This function is thread-safe (calling it from multiple threads does not introduce a data race) as long as no other function modifies the host environment. In particular, the POSIX functions |
(since C++11) |
Modifying the string returned by getenv invokes undefined behavior.
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[edit] Parameters
| env_var | - | null-terminated character string identifying the name of the environmental variable to look for |
[edit] Return value
Character string identifying the value of the environmental variable or null pointer if such variable is not found.
[edit] Notes
On POSIX systems, the environment variables are also accessible through the global variable environ, declared as extern char** environ; in <unistd.h>, and through the optional third argument, envp, of the main function.
[edit] Example
#include <cstdlib> #include <iostream> int main() { if (const char* env_p = std::getenv("PATH")) std::cout << "Your PATH is: " << env_p << '\n'; }
Possible output:
Your PATH is: /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games
[edit] See also
| C documentation for getenv
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