C check string's from a text file

Question

I am new at c and I am writing a code that get a string from the user and compare it to a strings from the text file and my code is only working when I compare between two characters and when I compare between two strings it's not working If someone know how can I fix the problem it's will be verey helpful. the compare line is in the searchFile function. the text file is a csv file so insted compare the char to string I need to compare between what befor the , to the string_to_search. example for csv file at the end of the code

Example: string to search = 'c' work, string to search 'name' doesn't work

#include <stdio.h>
#define STR_LEN 100

int searchFile(char* string_to_search, char* path);

int main(int argc, char* argv[])
{
    FILE* text_file = 0;
    int found = 0, choice = 0;
    char string_to_search[STR_LEN] = {0};
    if (!(fopen(argv[1], "r") == NULL)) //check if file exists
    {
        do 
        {
            printf("Please enter your choice:\n");
            printf("1 - Search a term in the document.\n");
            printf("2 - change a value in a specific place.\n");
            printf("3 - copy a value from one place to another\n");
            printf("4 - Exit\n");
            scanf("%d", &choice);
            getchar();
            switch (choice)
            {
                case 1:
                    fgets(string_to_search, STR_LEN, stdin);
                    string_to_search[strcspn(string_to_search, "\n")] = 0;
                    found = searchFile(string_to_search, argv[1]); //found = where the string line
                    if (found != 0)
                        printf("Value was found in row %d\n", found);
                    else
                        printf("Value Wasn't Found\n");
            }
        }while(choice != 4);
    }
    else
    {
        printf("file does not exists\n");
    }
    getchar();
    return 0;
}
int searchFile(char* string_to_search, char* path)
{
    FILE* file = fopen(path, "r");
    char ch = ' ';
    int i = 0, len = 0, count = 1;
    fseek(file, 0, SEEK_END);
    len = ftell(file);
    fseek(file, 0, SEEK_SET);
    len = len - 2;
    char* string = (char*)malloc(sizeof(char) * len);
    do //copying the chars to a string
    {
        ch = fgetc(file);
        string[i] = ch;
        i++;
    } while (ch != EOF);
    fclose(file);
    for (i = 0; i < len; i++)
    {
        if (string[i] == *string_to_search) //the compare
        {
            free(string);
            return count;
        }
        if (string[i] == '\n')
        {
            count++;
        }
    }
    free(string);
    return 0;
}

Example for a CSV file:

roee,itay,3,4
5,6,7,8
a,b,c,d
e,f,g,h

because it's give me error, strcmp not work with chars only string's i think — roee
– roee, Commented May 12, 2021 at 18:00
You compare characters with == and strings with strcmp() ... period. (unless you roll your own loop to mimic what strcmp() does...) — David C. Rankin
– David C. Rankin, Commented May 13, 2021 at 10:07

Andreas Wenzel · Accepted Answer · 2021-05-13 10:15:16Z

1

You have to change the following line:

if (string[i] == *string_to_search) //the compare

into

if (string[i] == string_to_search[i]) //the compare

The problem is that *string_to_search always refers to the first character of string_to_search. With the [i] you will get the nth character of the string as you have done it for the variable string. So as you noticed it works for a comparsion of two characters but not for two strings, because on a string you will always compare with the first character of string_to_search. For example if you want to compare "aaa" it will also work.

But as noted in the comment section you may also want to use strcmp() instead of the loop. There you will also have to pass string_to_search and not *string_to_search, because you want to pass the pointer to the string and not a single character.

edited May 13, 2021 at 10:15

Andreas Wenzel

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answered May 12, 2021 at 18:00

Benjamin J.

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6 Comments

roee Over a year ago

but it's work every time that the first character is the same like the string in the file will be 'roee' and the string_to_search will be 'rsd'. and what I am looking for is that it will be compare between 'roee' to 'roee' and not only the first char

roee Over a year ago

the file is a csv file

roee Over a year ago

so I need to compare between the string_to_search and the string before the ,

Benjamin J. Over a year ago

@roee: Maybe you should edit your question and give us a example CSV file and an example input for string_to_search.

roee Over a year ago

yea I did that know

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