Thread: Delete line when previous line is same

Hello, I would like to read a text file and delete those lines that occur twice. The single values are separated with a semicolon. I parse the data and distinguish by date. If the current date is the same as the previous one, this line should not be written into the new file "output".

Only at this point I don't know how to implement this in C. I currently try to skip this line with fgetc(fp)!='\n'; but this does not work.

My question. What do I have to insert instead of this line

Code:

fgetc(fp)!='\n'

in the code so that the duplicate line is not copied into the new file?

Code:

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

#define MAX_LINE_LENGTH 1000      // maximum length of a line in the input file

char lines[MAX_LINE_LENGTH];

int main()
{
    // Open the input file
    FILE *fp = fopen("input.txt", "r");
    if (fp == NULL)
    {
        printf("Failed to open the file.\n");
        return 1;
    }

        FILE *fpp = fopen("output.txt", "w");
    if (fp == NULL)
    {
        printf("Failed to open the file.\n");
        return 1;
    }


    int count =0;
    char ticker[50], dateActual[50], dateOld[50];
    char line[MAX_LINE_LENGTH];

    while ( (fgets(line, sizeof(line), fp) != NULL))
    {

        sscanf(line,"%[^;];%[^;];\n",ticker, dateActual);


        if(strcmp(dateActual,dateOld)==0)
        {
            fgetc(fp)!='\n';
        }

        fprintf(fpp, "line [%d]%s\n",count, line);
        memcpy(dateOld, dateActual, sizeof(dateActual));

        count++;

    }


    // Close the input and output file
    fclose(fp);

    return 0;
}

Just do

Code:

if ( strcmp(dateActual,dateOld) != 0 ) {
    // date is different, write it out.
    fprintf(fpp, "line [%d]%s\n",count, line);
}

You should also initialise dateOld to be a proper empty string to begin with.