The following function checks if a variable name start with a letter and may have preceding characters which are letters/ numbers. Why does the return value is always 1 no matter what the input is?
#include <regex.h>
#include <stdio.h>
int validate_var(char *str)
{
regex_t reg;
regcomp(®, "^[a-zA-Z]+[a-zA-Z0-9]*$", 0);
int r = regexec(®, str, 0, NULL, 0);
regfree(®);
return r;
}
int main() {
printf("%d\n", validate_var("abc")); // Reports 1, This makes sense
printf("%d\n", validate_var("17")); // Reports 1, This doesn't make sense
}
You're using anchors ( ^
and $
) but not enabling extended syntax by passing REG_EXTENDED
to regcomp()
. See the manual page .
You should really check all return values, there should be a failure reported somewhere due to the syntax usage error.
Note that non-zero means failure.
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