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.

strtoimax, strtoumax — convert string to integer type

#include <inttypes.h>
intmax_t strtoimax(const char *restrict nptr, char **restrict endptr,

int base); uintmax_t strtoumax(const char *restrict nptr, char **restrict endptr,
int base);

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.

These functions shall be equivalent to the strtol(), strtoll(), strtoul(), and strtoull() functions, except that the initial portion of the string shall be converted to intmax_t and uintmax_t representation, respectively.

These functions shall return the converted value, if any.

If no conversion could be performed, zero shall be returned and errno may be set to [EINVAL].

If the value of base is not supported, 0 shall be returned and errno shall be set to [EINVAL].

If the correct value is outside the range of representable values, {INTMAX_MAX}, {INTMAX_MIN}, or {UINTMAX_MAX} shall be returned (according to the return type and sign of the value, if any), and errno shall be set to [ERANGE].

These functions shall fail if:

The value of base is not supported.
The value to be returned is not representable.

These functions may fail if:

No conversion could be performed.

The following sections are informative.


Since the value of *endptr is unspecified if the value of base is not supported, applications should either ensure that base has a supported value (0 or between 2 and 36) before the call, or check for an [EINVAL] error before examining *endptr.



strtol(), strtoul()

The Base Definitions volume of POSIX.1‐2017, <inttypes.h>

Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at .

Any typographical or formatting errors that appear in this page are most likely to have been introduced during the conversion of the source files to man page format. To report such errors, see .

2017 IEEE/The Open Group