---
name: "atoll"
section: "3"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["linux", "freebsd"]
url: "https://new.carta.tech/atol"
---

# atoll(3)

convert ASCII string to long or long long integer

Part of [atol(3)](/atol/3.md).

## NAME

**atol**, **atoll** – convert ASCII string to *long* or *long long* integer

## LIBRARY

Standard C Library (libc, -lc)

## SYNOPSIS

**#include \<stdlib.h\>**

*long*\

**atol**(*const char \*nptr*);

*long long*\

**atoll**(*const char \*nptr*);

## DESCRIPTION

The **atol**() function converts the initial portion of the string pointed to by *nptr* to *long* integer representation.

It is equivalent to:

```
strtol(nptr, (char **)NULL, 10);
```

The **atoll**() function converts the initial portion of the string pointed to by *nptr* to *long long* integer representation.

It is equivalent to:

```
strtoll(nptr, (char **)NULL, 10);
```

## COMPATIBILITY

The FreeBSD implementations of the **atol**() and **atoll**() functions are thin wrappers around **strtol**() and **strtoll**() respectively, so these functions will affect the value of *errno* in the same way that the **strtol**() and **strtoll**() functions are able to. This behavior of **atol**() and **atoll**() is not required by ISO/IEC 9899:1990 (“ISO C90”) or ISO/IEC 9899:1999 (“ISO C99”), but it is allowed by all of ISO/IEC 9899:1990 (“ISO C90”), ISO/IEC 9899:1999 (“ISO C99”) and IEEE Std 1003.1-2001 (“POSIX.1”).

## ERRORS

The functions **atol**() and **atoll**() may affect the value of *errno* on an error.

## SEE ALSO

[atof(3)](/atof/3.md), [atoi(3)](/atoi/3.md), [strtod(3)](/strtod/3.md), [strtol(3)](/strtol/3.md), [strtoul(3)](/strtoul/3.md)

## STANDARDS

The **atol**() function conforms to ISO/IEC 9899:1990 (“ISO C90”). The **atoll**() function conforms to ISO/IEC 9899:1999 (“ISO C99”).