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

int main(void) {

    // Vars for file names to be given by user
    char inputFileName[50];
    char outputFileName[50];

    char linesInFile[100];
    int numRead;
    char* subString;

    // FILE* struct vars for each file
    FILE* inFile = NULL;
    FILE* outFile = NULL;

    // Prompt/scan input file name
    printf("Input file name:\n");
    scanf("%s", inputFileName);

    // Prompt/scan output file name
    printf("Output file name:\n");
    scanf("%s", outputFileName);

    // Open each file
    inFile = fopen(inputFileName, "r");
    outFile = fopen(outputFileName, "w");

    // Error check fopen()
    if (inFile == NULL) {
        printf("fopen() failed to open the file \"%s\".\n", inputFileName);
        return -1;
    }
    if (outFile == NULL) {
        printf("fopen() failed to open the file \"%s\".\n", outputFileName);
        return -1;
    }

    // Read 1 line from input file
    numRead = fscanf(inFile, "%s", linesInFile);

    // Loop through lines in file
    while (!feof(inFile)) {
        if (numRead == 1) {
            subString = strstr(linesInFile, "photo.jpg");
            strcpy(subString, "info.txt");
            fprintf(outFile, "%s\n", linesInFile);
            numRead = fscanf(inFile, "%s", linesInFile);
        } else {
            printf("Input failure before end of file was reached.\n");
            break;
        }
    }

    // Close each file
    fclose(inFile);
    fclose(outFile);
    
    return 0;

}