循环打印数组内容时程序挂起

Question

Hi, i am using the MinGW C Compiler with Code::Blocks and my code hangs when trying to print the contents of an array (well it is a custom data type). For a quick summary: the program is taking the contents of a txt file and splits the string up into individual words using a custom data type called a stringArray (the name explains itself). It then should print each word of the file to the user. The problem is, it hangs and gives me the usual "[PROGRAM NAME HERE] is not responding." After pressing cancel it gives me this result:

Process returned -1073741819 (0xC0000005) execution time : 3.861 s Press any key to continue.

I am a sort of beginner.

Here is the code:

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

typedef struct stringArray
{
   char *string;

}stringArray;

const char delim[2] = " ";

int string_to_array(char *filecontents)
{
    char *token;
    token = strtok(filecontents, delim);

    int i;
    int dirtyContentsLength;
    stringArray newContents[100];

    for(i = 0; i < 100; i++)
    {
        newContents[i].string = "";
    }

    i = 0;

    while (token != NULL)
    {
        newContents[i].string = token;
        i++;
        token = strtok(NULL, delim);
    }

    return newContents;
}

int open_file(char filename[30])
{
    char *file_contents;
    long input_file_size;
    FILE *input_file = fopen(filename, "rb");
    fseek(input_file, 0, SEEK_END);
    input_file_size = ftell(input_file);
    rewind(input_file);
    file_contents = malloc(input_file_size * (sizeof(char)));
    fread(file_contents, sizeof(char), input_file_size, input_file);
    fclose(input_file);

    return file_contents;
}

int lex(char filecontents[30])
{
    char *tok = "";
    int state = 0;
    char *string = "";

}

int main(int argc, char *argv[] )
{
    const char *cleanContents;
    char *messyContents;
    char input[30];
    printf("What is the filename? ");
    scanf("%s", input);
    messyContents = open_file(input);
    cleanContents = string_to_array(messyContents);

    int contentsLength = sizeof(cleanContents) / sizeof(cleanContents[0]);
    int i;
    for(i = 0; i < contentsLength; i++)
    {
        printf("%s\n", cleanContents[i]);
    }

    printf("Done");
    return 0;


}

Answer 1

You have multiple problems with your code:

1. string_to_array() is declared to return an int , but in reality it is returning a stringArray
2. Same with open_file() function, Declared to return an int , but actually returning a char*
3. string_to_array is returning an element that was declared locally. This means that once the function is returned, that memory is no longer valid, but it has passed it on to the caller.
4. Your structure name is misleading. A char* is a character array (a string). Thus the name charArray would be more appropriate. For the structure to be a string array it has to be a char** , ie an array of character arrays (array of strings)
5. Int the printf() in the main() function you are not passing the string (thus a compilation warning is generated)
6. You are not initializing memory to all 0. This is ideal as otherwise the memory will contain random data which will be interpreted as a string untill the first null terminator ( \\0 encountered)

The following code is a modified working version of what you are trying to achieve with comments about each change:

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

typedef struct stringArray
{
   char *string;

}stringArray;

const char delim[2] = " ";

// Now string_to_array takes the memory location to write output to as a first parameter so that the
// memory will reside in the callers scope (refer to problem 3 above)
// Additionally return type was now set to void (refer to problem 1)
void string_to_array(stringArray newContents[100], char *filecontents)
{
    char *token;
    token = strtok(filecontents, delim);

    int i;
    int dirtyContentsLength;

    for(i = 0; i < 100; i++)
    {
        newContents[i].string = "";
    }

    i = 0;

    while (token != NULL)
    {
        newContents[i].string = token;
        i++;
        token = strtok(NULL, delim);
    }

    // return now was removed. result written directly in memory passed as parameter by the caller.
}

// open_file changed to return a char* (refer to problem 2)
char* open_file(char filename[30])
{
    char *file_contents;
    long input_file_size;
    FILE *input_file = fopen(filename, "rb");
    fseek(input_file, 0, SEEK_END);
    input_file_size = ftell(input_file);
    rewind(input_file);
    file_contents = malloc(input_file_size * (sizeof(char)));
    fread(file_contents, sizeof(char), input_file_size, input_file);
    fclose(input_file);

    return file_contents;
}

int lex(char filecontents[30])
{
    char *tok = "";
    int state = 0;
    char *string = "";

}

int main(int argc, char *argv[] )
{
    stringArray cleanContents[100];
    // Initializing memory to all 0s (refer to problem 6)
    memset(cleanContents, 0 ,sizeof(cleanContents));
    char *messyContents;
    char input[30];
    printf("What is the filename? ");
    scanf("%s", input);
    messyContents = open_file(input);
    string_to_array(cleanContents, messyContents);

    int contentsLength = sizeof(cleanContents) / sizeof(cleanContents[0]);
    int i;
    for(i = 0; i < contentsLength; i++)
    {
        // Checking that at least one character is present in the string before printing it...
        if (cleanContents[i].string[0])
        {
            // Printing the string within the 'stringArray'. (refer to problem 5)
            printf("%s\n", cleanContents[i].string);
        }
    }

    printf("Done\n");
    return 0;


}