strtoimax - Man Page

convert string to integer type


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.


#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.

Return Value

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.



Application Usage

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.



Future Directions


See Also

strtol(), strtoul()

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

Referenced By


2017 IEEE/The Open Group POSIX Programmer's Manual