CODEWITHSUNDEEP
cpointerslowercase
Real Name
Real Name

Reputation: 19

How do I fix this issue I'm having with my lowercase function

I'm trying to make a function that goes through a linked list and finds all strings that contain a substring that the user inputs.

The problem is that its case sensitive and I need it to not be. My idea was to make everything lowercase while going through the list. And wrote something that should work... I think... but doesn't

char *lowerCase(char* strToLower){
    char *lowCase;
    strcpy(lowCase, strToLower);
    for(int i = 0; lowCase[i]; i++){
       lowCase[i] = tolower(lowCase[i]);
    }
    return lowCase;
}

printf("%s", lowerCase("Name"));

Now, what ideally should pop up is "name", but I instead get nothing.

I get Process returned -1073741819 (0xC0000005), which I think is an error related to pointers or memory? I don't really know because build log doesn't tell me anything.

Any help is appreciated <3

Upvotes: 0

Views: 44

Answers (1)

Nidhoegger
Nidhoegger

Reputation: 5232

The Problem is that you use strcpy wrong. Please refer to the manpage: https://linux.die.net/man/3/strcpy

You need to actually allocate a buffer for the copied string. You right now just copy it to a random memory location (as lowCase is not initialized).

You need to so:

char *lowerCase(char* strToLower){
    char *lowCase = (char *)malloc(strlen(strToLower) + 1); // +1 because of terminator
    strcpy(lowCase, strToLower);
    for(int i = 0; lowCase[i]; i++){
       lowCase[i] = tolower(lowCase[i]);
    }
    return lowCase;
}

and it should work. But beware: As lowCase was allocated, you also need to free it after use, otherwise you have a memory leak.

Upvotes: 2

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