isdigit
From cppreference.com
| Defined in header <ctype.h>
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int isdigit( int ch );
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Checks if the given character is a numeric character (0123456789).
The behavior is undefined if the value of ch is not representable as unsigned char and is not equal to EOF.
Parameters
| ch | - | character to classify |
Return value
Non-zero value if the character is a numeric character, zero otherwise.
Notes
isdigit and isxdigit are the only standard narrow character classification functions that are not affected by the currently installed C locale, although some implementations (e.g. Microsoft in 1252 codepage) may classify additional single-byte characters as digits.
Example
Run this code
#include <ctype.h>
#include <limits.h>
#include <stdio.h>
int main(void)
{
for (int ndx = 0; ndx <= UCHAR_MAX; ++ndx)
if (isdigit(ndx))
printf("%c", ndx);
printf("\n");
}
Output:
0123456789
References
- C23 standard (ISO/IEC 9899:2024):
- 7.4.1.5 The isdigit function (p: TBD)
- C17 standard (ISO/IEC 9899:2018):
- 7.4.1.5 The isdigit function (p: 146)
- C11 standard (ISO/IEC 9899:2011):
- 7.4.1.5 The isdigit function (p: 201)
- C99 standard (ISO/IEC 9899:1999):
- 7.4.1.5 The isdigit function (p: 182)
- C89/C90 standard (ISO/IEC 9899:1990):
- 4.3.1.4 The isdigit function
See also
(C95) |
checks if a wide character is a digit (function) |
C++ documentation for isdigit
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