`atoi.3p` ( 3 )

преобразовать строку в целое число (convert a string to an integer)

Пролог (Prolog)

This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

Имя (Name)

atoi — convert a string to an integer

Синопсис (Synopsis)

#include <stdlib.h>

int atoi(const char *str);

Описание (Description)

The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the requirements described here and the ISO C standard is unintentional. This volume of POSIX.1‐2017 defers to the ISO C standard.

The call atoi(str) shall be equivalent to:

(int) strtol(str, (char **)NULL, 10)

except that the handling of errors may differ. If the value cannot be represented, the behavior is undefined.

Возвращаемое значение (Return value)

The atoi() function shall return the converted value if the value can be represented.

Ошибки (Error)

No errors are defined.

The following sections are informative.

Примеры (Examples)

Converting an Argument
       The following example checks for proper usage of the program. If
       there is an argument and the decimal conversion of this argument
       (obtained using atoi()) is greater than 0, then the program has a
       valid number of minutes to wait for an event.

           #include <stdlib.h>
           #include <stdio.h>
           ...
           int minutes_to_event;
           ...
           if (argc < 2 || ((minutes_to_event = atoi (argv[1]))) <= 0) {
              fprintf(stderr, "Usage: %s minutes\n", argv[0]); exit(1);
           }
           ...

Использование в приложениях (Application usage)

The atoi() function is subsumed by strtol() but is retained because it is used extensively in existing code. If the number is not known to be in range, strtol() should be used because atoi() is not required to perform any error checking.

Обоснование (Rationale)

None.

Будущие направления (Future directions)