Comparing string to arry of strings

This is a discussion on Comparing string to arry of strings within the C Programming forums, part of the General Programming Boards category; Hello there, I'm new to C programming and I have the following exercise to do: "Consider an array v[0, 1,..., ...

  1. #1
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    Comparing string to arry of strings

    Hello there,

    I'm new to C programming and I have the following exercise to do:

    "Consider an array v[0, 1,..., (n-1)] whose elements are strings. Remember that, in C a string is just an array of chars ending with the null character '\0'. So, you can suppose that v was declared this way: char *v[n]. Write a function that receives a string x and returns a index j in which x = v[j]. If this j doesn't exist, the function must return -1."

    Here's what I did:

    Code:
    #include <stdio.h>
    #include <string.h>
    
    int contem(char string, char *v, int n) {
    
        int i;
    
        for (i = 0; i < 10; i++) {
            if (strcmp(v[i], string) == 0) {
                return i;
            }
        }
    
        return -1;
    
    }
    
    main() {
    
        char *v[10];
        v[0] = "File";
        v[1] = "Edit";
        v[2] = "View";
        v[3] = "Search";
        v[4] = "Tools";
        v[5] = "Documents";
        v[6] = "Help";
        v[7] = "Open";
        v[8] = "Save";
        v[9] = "Undo";
        
        char string [100];
    
        printf("String to search for: ");
        gets(string);
    
        int ret = contem(string, v, 10);
    
        if (ret == -1) {
                printf("The string is not in the array.");
                return 0;
        }
    
        else printf("The string is at position: ", ret);
    
        return 0;
    
    }
    I get the following warnings:

    warning: passing argument 1 of 'strcmp' makes pointer from integer without a cast

    warning: passing argument 2 of 'strcmp' makes pointer from integer without a cast

    warning: passing argument 1 of 'contem' makes integer from pointer without a cast

    warning: passing argument 2 of 'contem' from incompatible pointer type



    What am I doing wrong? Does the array v must really be declared as a pointer?

    Thanks in advance.

    Regards,
    Samir

  2. #2
    C++ Witch laserlight's Avatar
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    What is the type of v[i]? What is the types of the parameters of strcmp?
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  3. #3
    and the hat of wrongness Salem's Avatar
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    It needs to be declared as an array of pointers (for that is what you're passing).

    int contem(char string, char *v[], int n)
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
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    v is declared like this:
    char *v[10];

    After I have added the [] to the second argument of the contem function I got only two warnings:
    warning: passing argument 2 of 'strcmp' makes pointer from integer without a cast

    warning: passing argument 1 of 'contem' makes integer from pointer without a cast

    Is it that I am comparing a pointer to a char?
    Last edited by Samir Aguiar; 03-12-2012 at 11:52 PM.

  5. #5
    Technical Lead QuantumPete's Avatar
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    Quote Originally Posted by Samir Aguiar View Post
    Is it that I am comparing a pointer to a char?
    Yes indeed! Check what parameter types strcmp takes and then check what you're passing into it. Also the first parameter you're passing into contem() isn't right.
    Lastly, don't use gets() !
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  6. #6
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    Now I get it. v is declared as an array of pointers to char (char * v[]) while string is declared as an array of chars. I was passing to function contem v as a pointer to char and string as a char.
    I have changed contem arguments to this:

    int contem(char string[], char * v[], int n);

    And it solved the problem. Thanks for the help guys, I appreciate it!

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