将struct值与变量进行比较

Question

I'm struggling to compare the contents of a struct to a variable. There are 10 structs in array1 with the variables value and count. I need to go through every value variable until I find the one matching tempVal and then increment the corresponding count, then the search can end. If it's not found the function will return -1.

I have the following code that runs fine but doesn't work, I have a feeling it may be something wrong with the strcmp line but I'm not sure. Cheers for any input.

int valCheck(char *tempVal){

    int j;
    for(j=0;j<10;j++){
        if(strcmp(array1[j].value, tempVal) == 0){ 
            array1[j].count++; //increment its count
            break;

        }
    }
}

Edited full:

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>

struct values
{
    char value[64];
    int count;
};

struct values array1[100];

//check if value exists in array
int valCheck(char *tempVal)
{
    int j;
    for(j=0;j<10;j++)
    {
        if(strcmp(array1[j].value, tempVal) == 0)
        {
            array1[j].count++; //increment its count
            //return j; // <== return index of found element
        }
    }
    return -1;
}

int main()
{
    FILE * input;
    int i;
    char tempVal[] ="hello";
    input = fopen("random.txt","r");

    for (i=0;i<=10;i++) //go through the 10 elements in text file
    {
        //scan each word into a temporary variable
        // **** NOT COMPLETE, JUST USING TEMPWORD ASSIGNED FOR NOW

        int checkedVal = valCheck(&tempVal);

        //if wordCheck returns -1 add the word to the array
        //otherwise do nothing as a duplicate has appeared
        if(checkedVal == -1){
            fscanf(input, "%s",array1[i].value);
        }

        printf("WORD %i: %s ",i,array1[i].value);
        printf(" COUNT IS: %i", array1[i].count);
        printf("\n");
    }

    fclose(input);
    return 0;
}

Answer 1

Assuming the following:

• Your array is properly allocated (either on the stack or dynamically) to be at-least-10-elements wide.
• Your structure member value is a valid char * or fixed-length char[n] buffer.
• The string data references by the value member of your structure is properly null-terminated.
• The string data referenced by tempVal is valid and properly null-terminated.
• You're aware that strcmp() compares case-sensitively
• You're comment about 100 elements in the array and this code only checking the first ten (10) elements is intentional

My crystal ball tells me that ultimately you need to have your function actually return something.

int valCheck(char *tempVal)
{
    int j;
    for(j=0;j<10;j++)
    {
        if(strcmp(array1[j].value, tempVal) == 0)
        { 
            array1[j].count++; //increment its count
            return j; // <== return index of found element
        }
    }
    return -1;  // <== return -1 per your description of failure.
}

Note: Your compiler, equipped with decent warning-checks, would easily spot this lack-of-return code. Heed those warnings. Likewise, double-check everything in the bullet list at the top of this answer to make sure what you're going into this with is proper.

---

EDIT Updated to reflect sample dictionary build for OP.

The following is how I think this is likely to be called. Hope it helps you. I changed a few things:

• Made the dictionary a little bigger (256)
• Processes the command line to get the filename. Makes it easier for me to test.
• Only reports a summary at the end rather than per-word while processing.

I hope it helps.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>

struct values
{
    char value[64];
    int count;
};

// global array.
struct values array1[256];
int n_words = 0;

//check if value exists in array
int valCheck(const char *tempVal)
{
    int j;
    for(j=0;j<10;j++)
    {
        if(strcmp(array1[j].value, tempVal) == 0)
        {
            array1[j].count++; //increment its count
            return j;
        }
    }
    return -1;
}

int main(int argc, char *argv[])
{
    FILE * input = NULL;
    char tempVal[64];
    int i=0;

    if (argc < 2)
    {
        printf("Must specify a filename.\n");
        return EXIT_FAILURE;
    }

    // open file
    input = fopen(argv[1],"r");
    if (!input)
    {
        perror("Failed to open file.");
        return EXIT_FAILURE;
    }

    // read all strings from the file one at a time.
    while (fscanf(input, "%64s", tempVal) == 1)
    {
        int i = valCheck(tempVal);
        if (i == -1)
        {
            if (n_words < sizeof(array1)/sizeof(array1[0]))
            {
                strcpy(array1[n_words].value, tempVal);
                array1[n_words].count = 1;
                i = n_words++;
            }
            else
            {   // error. no more space in dictionary
                printf("No more space to add word: %s\n", tempVal);
            }
        }

    }
    fclose(input);

    // summary report
    for (i=0;i<n_words;++i)
        printf("WORD %i: %s, COUNT IS: %i\n", i, array1[i].value, array1[i].count);

    return EXIT_SUCCESS;
}

Input

hello my name is dave hello I am dave hi

Output

WORD 0: hello, COUNT IS: 2
WORD 1: my, COUNT IS: 1
WORD 2: name, COUNT IS: 1
WORD 3: is, COUNT IS: 1
WORD 4: dave, COUNT IS: 2
WORD 5: I, COUNT IS: 1
WORD 6: am, COUNT IS: 1
WORD 7: hi, COUNT IS: 1

---

Homework

After all of that, I leave you to determine why the following code also works, but uses no temporary buffer to do so (sort of, anyway).

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>

struct values
{
    char value[64];
    int count;
};

// global array.
#define MAX_WORDS   256
struct values array1[MAX_WORDS] = {{{0},0}};
int n_words = 0;

//check if value exists in array
int valCheck(const char *tempVal)
{
    int j;
    for(j=0; j< n_words; j++)
    {
        if(strcmp(array1[j].value, tempVal) == 0)
        {
            array1[j].count++; //increment its count
            return j;
        }
    }
    return -1;
}

int main(int argc, char *argv[])
{
    FILE * input = NULL;
    int i=0;

    if (argc < 2)
    {
        printf("Must specify a filename.\n");
        return EXIT_FAILURE;
    }

    // open file
    input = fopen(argv[1],"r");
    if (!input)
    {
        perror("Failed to open file.");
        return EXIT_FAILURE;
    }

    // read all strings from the file one at a time.
    while (n_words < MAX_WORDS &&
           fscanf(input, "%64s", array1[n_words].value) == 1)
    {
        if (valCheck(array1[n_words].value) == -1)
        {
            array1[n_words].count = 1;
            ++n_words;
        }
    }
    fclose(input);

    // summary report
    for (i=0;i<n_words;++i)
        printf("WORD %i: %s, COUNT IS: %i\n", i, array1[i].value, array1[i].count);

    return 0;
}

The output is the same as before.