printing "\n" every ten characters and also at the end of a file.

Hi guys! I am working on another assignment and I need your help. I am having trouble printing a \n every ten characters in the output file and also at the end of the output file. The reason you see all of those include files is because that this is a multi-file project.

Code:

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#include <stdio.h>
#include <windows.h>
#include "proto.h"
#include <stdlib.h>
#include <malloc.h>

int main(int argc, char *argv[]) //check for command line arguments//
{
        FILE *inputFile; //pointer to a file//
        char * memBlock; //memory pointer//
        int count; //counter variable//
        int fileSize = 0; //file size variable//
        FILE *outputFile; //output file pointer//

inputFile = fopen(argv[1], "rb"); //open a binary file for reading//


        if (inputFile == NULL)
        {
                printf("Cannot open file for reading.\n"); //display error if file is not found//
                return -1;
        }

       
fileSize = getSmallFileLength(argv[1]); //input filename as a parameter//


        if (argv[1] == NULL)
        {
                return -2; //if size is less than 1 quit the program//
        }
       
memBlock = (char*) malloc(fileSize); //memory allocated for file//

        if (memBlock == NULL) //if no memory avalible display error message//
        {
                printf("Error: Not Enough Memory.\n");
        }
        else
        {
                fread(memBlock, sizeof(char*), fileSize, inputFile); //read in the entire file//
                fclose(inputFile); //done with file//

                outputFile = fopen("contents.txt", "w"); //open empty file for wrting//
                if (outputFile == NULL)
                {
                        printf("Cannot open file for writing.\n"); //if file not avalible display error//
                }
                        for (count = 0; count < fileSize; count++) //i is less than the fileSize, increment i, and add 1 to i//
                        {
                                fprintf(outputFile, "%03d ",*(memBlock+count)); //prints out the ASCII values ome-by-one//
                        }

                        if (count % 10)
                        {
                                fprintf(outputFile, "\n"); //print a \n every ten characters//
                        }

                free(memBlock); //free allocated memory block//
        }

        fprintf(outputFile, "\n"); //print a \n at the end of the file//

        fclose(outputFile); //done with output file//

        return 0;
} // end of main //

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You can put the conditional evaluation right inside the fprintf() statement as in

Code:

---

for (count = 0; count < fileSize; count++) //i is less than the fileSize, increment i, and add 1 to i//
{
    fprintf(outputFile, (count % 10 ? "%03d " : "\n"), *(memBlock+count)); //prints out the ASCII values ome-by-one//
}

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That does not work right. The letter a (ASCII 97) does not print out in the output file.

Your posted code seems very close, what problem do you have when you run it?

Code:

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        else
        {
                fread(memBlock, sizeof(char*), fileSize, inputFile); //read in the entire file//
                fclose(inputFile); //done with file//

                outputFile = fopen("contents.txt", "w"); //open empty file for wrting//
                if (outputFile == NULL)
                {
                        printf("Cannot open file for writing.\n"); //if file not avalible display error//
                }
               
                //this for loop is indented wrong. It should be one level further to the left.
                //like so. Also, there is no i variable in this loop.
                for (count = 0; count < fileSize; count++) //i is less than the fileSize, increment i, and add 1 to i//
                        {
                                fprintf(outputFile, "&#37;03d ",*(memBlock+count)); //prints out the ASCII values one-by-one//
                        }
                        //you're testing after the 10th char has already been printed.
                        //That's too late! Test *before* the 10th char has printed, instead.
                        if (count % 10) //change it to if(count % 10 == 0 && count > 0)
                        {
                                fprintf(outputFile, "\n"); //print a \n every ten characters//
                        }

                free(memBlock); //free allocated memory block//
        }

        fprintf(outputFile, "\n"); //print a \n at the end of the file//

        fclose(outputFile); //done with output file//

        return 0;
} // end of main //

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That will fix it, I believe.

Quote:

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Originally Posted by Sgemin_001

That does not work right. The letter a (ASCII 97) does not print out in the output file.

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When count is zero just printout the ASCII value as in

Code:

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for (count = 0; count < fileSize; count++)
{
    if (count == 0)
        fprintf(outputFile, "%03d ", *(memBlock+count));
    else
        fprintf(outputFile, (count % 10 ? "%03d " : "\n"), *(memBlock+count));
}

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Other way around, I believe.

Code:

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if(count % 10 == 0 && count > 0)
      fprintf the newline.
else
      fprintf the ascii value.

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By the way, malloc() and free() are available via <stdlib.h>, not <malloc.h>.

Thanks for the replies. That part works fine now. But one other thing, I my program crashes if you d not have anything as the file name for input, and I don't know how to fix it, Any ideas?

That's expected behavior since fopen() can't deal with a NULL filename. To avoid crashing check if argv[1] is not NULL else exit the program cleanly.