atoi, atol, atoll
From cppreference.com
Defined in header <stdlib.h>
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int atoi( const char *str ); |
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long atol( const char *str ); |
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long long atoll( const char *str ); |
(since C99) | |
Interprets an integer value in a byte string pointed to by str
.
Discards any whitespace characters until the first non-whitespace character is found, then takes as many characters as possible to form a valid integer number representation and converts them to an integer value. The valid integer value consists of the following parts:
- (optional) plus or minus sign
- numeric digits
Parameters
str | - | pointer to the null-terminated byte string to be interpreted |
Return value
Integer value corresponding to the contents of str
on success.
If no conversion can be performed, 0 is returned.
If the value of the result cannot be represented, i.e. the converted value falls out of range of the corresponding return type, behavior is undefined.
Notes
The name stands for "ASCII to integer".
Example
Run this code
Output:
-123 0 0 -2147483648
References
- C11 standard (ISO/IEC 9899:2011):
- 7.22.1.2 The atoi, atol, and atoll functions (p: 341)
- C99 standard (ISO/IEC 9899:1999):
- 7.20.1.2 The atoi, atol, and atoll functions (p: 307)
- C89/C90 standard (ISO/IEC 9899:1990):
- 4.10.1.2 The atoi function
- 4.10.1.3 The atol function
See also
(C99) |
converts a byte string to an integer value (function) |
(C99) |
converts a byte string to an unsigned integer value (function) |