Test a character to see if it's a decimal digit
#include <ctype.h> int isdigit( int c );
libc
Use the -l c option to qcc to link against this library. This library is usually included automatically.
The isdigit() function tests for a decimal digit (characters 0 through 9).
Nonzero if c is a decimal digit; otherwise, zero.
#include <stdio.h> #include <stdlib.h> #include <ctype.h> char the_chars[] = { 'A', '5', '$' }; #define SIZE sizeof( the_chars ) / sizeof( char ) int main( void ) { int i; for( i = 0; i < SIZE; i++ ) { if( isdigit( (unsigned)the_chars[i] ) ) { printf( "Char %c is a digit character\n", the_chars[i] ); } else { printf( "Char %c is not a digit character\n", the_chars[i] ); } } return EXIT_SUCCESS; }
produces the output:
Char A is not a digit character Char 5 is a digit character Char $ is not a digit character
Safety: | |
---|---|
Cancellation point | No |
Interrupt handler | Yes |
Signal handler | Yes |
Thread | Yes |