CODEWITHSUNDEEP
cregex
Kevin Mahendra
Kevin Mahendra

Reputation: 109

Match string using regex in C language (ignore case-sensitivity)

This is my code:

#include <string.h>
#include <ctype.h>
#include <stdio.h>
#include <regex.h>

int main(void)
{
    char name[]= "Michael Corleone";
    char inputName[40];

    regex_t regex;
    int return_value;

    printf("Enter name: ");
    fgets(inputName, sizeof(inputName), stdin);
    // Remove new line from fgets
    inputName[strcspn(inputName, "\n")] = 0;
    
    // Regcomp string input by user as pattern
    return_value = regcomp(&regex, inputName, 0);
    // Regexec string that will match against user input
    return_value = regexec(&regex, name, 0, NULL, 0);

    if (return_value == REG_NOMATCH)
    {
        printf("Pattern not found.\n");
        return 1;
    }
    else
    {
        printf("%s\n", name);
    }
}

I try to match a string using regex. As you can see, my code works pretty well. There's a person store in array named Michael Corleone. Then, when user try to input: Michael or Corleone or Michael Corleone it will matched and print the full name!

But the problem is case-sensitivity. If user try to input those name in lowercase it will failed.

I try to use this inside regcomp: regcomp(&regex, "[a-zA-Z][inputName]", 0); It works when i try to type the name in lowercase. But then i found out, it also works when i type another name like John, Leon, or Angel. So, i think it match everything that is alphabets.

Do you guys have the solution, please? Thank You!

Upvotes: 3

Views: 548

Answers (1)

Wiktor Stribiżew
Wiktor Stribiżew

Reputation: 627083

You need to replace the last argument to regcomp function (which is 0 now) with REG_ICASE:

return_value = regcomp(&regex, inputName, REG_ICASE); // 0 replaced with REG_ICASE

See the C demo.

From the regcomp documentation:

REG_ICASE
Do not differentiate case. Subsequent regexec() searches using this pattern buffer will be case insensitive.

Upvotes: 4

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