atol(3C)
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atol function
Convert an ASCII string to type long.
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Calling Sequence
long result, atol();
char *string;
result = atol(string);
where result is of type long.
string is a byte pointer to a character array that
contains optional spaces, an optional plus or minus
sign, and a string of digits.
Description
Use the atol function to convert an ASCII string to type long.
The function ignores leading whitespace (blanks or tabs) and
stops scanning at the first nondigit it encounters. The function
follows C conventions for radix specification.
The include file dg_stdio.h defines this function.
Returns
The atol function returns the type long integer that it converted
the string to. No errors are flagged on the atol call. If the
string is not numeric, the function atol returns 0.
Related Functions
See also the atof, atoi, atou, and strtol functions.
Example
/* Program test for the atol() function */
#include <stdio.h>
#include <math.h>
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atol(3C)
long result, atol();
long i = 1;
main(argc, argv)
int argc;
char *argv[];
{
while (i < argc) {
printf("The result from %s is %ld.\n", argv[i],
result = atol(argv[i]));
i++;
}
}
If you call the program test with the input numbers
2001
-2001
2001
20-01
MM1
you generate the output
The result from 2001 is 2001.
The result from -2001 is -2001.
The result from 2001 is 2001.
The result from 20-01 is 20.
The result from MM1 is 0.
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