std::getenv

 

C++

Linguaggio

Concetti

Libreria di Utilità

Stringhe

Contenitori

Algoritmi

Iteratori

Libreria matematca

Input/output

Localizzazione

Espressioni regolari(C++11)

Operazioni atomicche(C++11)

Multithreading(C++11)

 

Utilità libreria

Tipo di supporto (basic types, RTTI, type traits)

Gestione della memoria dinamica

La gestione degli errori

Programma di utilità

Funzioni variadic

Data e ora

Funzione oggetti

initializer_list (C++11)

bitset

hash (C++11)

Gli operatori relazionali Original: Relational operators The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

rel_ops::operator!= rel_ops::operator> rel_ops::operator<= rel_ops::operator>=

Coppie e tuple Original: Pairs and tuples The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

pair

tuple (C++11)

piecewise_construct_t (C++11)

piecewise_construct (C++11)

Swap, in avanti e spostare Original: Swap, forward and move The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

swap

forward (C++11)

move (C++11)

move_if_noexcept (C++11)

declval (C++11)

 

Programma di supporto utilità

Programma di terminazione Original: Program termination The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
abort exit quick_exit (C++11) _Exit (C++11)	atexit at_quick_exit (C++11) EXIT_SUCCESS EXIT_FAILURE
Comunicante con l'ambiente Original: Communicating with the environment The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
system	getenv
Segnali Original: Signals The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
signal raise sig_atomic_t	SIG_DFL SIG_IGN SIG_ERR
Tipi di segnale Original: Signal types The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
SIGABRT SIGFPE SIGILL SIGINT SIGSEGV SIGTERM
Non locali salti Original: Non-local jumps The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
setjmp
longjmp
Tipi Original: Types The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
jmp_buf

 

Elemento definito nell'header <cstdlib>
constchar*getenv(constchar*env_var );

Cerca un variabile ambientale con env_var nome nella lista di host specificato ambiente e restituisce le informazioni ad esso associati. L'insieme di variabili ambientali e metodi di alterarla sono definiti dall'implementazione.

Original:

Searches for an environmental variable with name env_var in the host-specified environment list and returns information associated with it. The set of environmental variables and methods of altering it are implementation-defined.

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Parametri

env_var

-

terminazione null stringa di caratteri che identifica il nome della variabile d'ambiente per cercare Original: null-terminated character string identifying the name of the environmental variable to look for The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

Valore di ritorno

Stringa di caratteri che identifica il valore della variabile ambientale o NULL se tale variabile non viene trovato.

Original:

Character string identifying the value of the environmental variable or NULL if such variable is not found.

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Esempio

#include <iostream>#include <cstdlib>   int main(int argc, char*argv[]){std::cout<<"Your PATH is: "<< std::getenv("PATH")<<std::endl;}

Possible output:

Your PATH is: /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games

Vedi anche

C documentation for getenv