Segmentation fault below certain character length

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C

file

Handling

Hello, I am doing a assignment. The task is:

Quote:

Open a text file and print its contents in command window, ask the user to replace the text from the text file to be written and save the text file.

The program works find till the character length 170 and above. when I define the character below 170 it is showing segmentation fault, that too when I open debugger and check the error. Are there any ways to overcome this problem. what are changes do I need to perform for smaller lengths.

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

#define MAX 170

  int main()
  {
        FILE *fptr1, *fptr2;
        int lno, linectr = 1;
        char str,fname[MAX];
        char newln[MAX], temp[] = "temp.txt";

		printf("\n\n Replace a specific line in a text file with a new text :\n");
		printf(" Input the file name to be opened : ");
        fgets(fname, MAX, stdin);
        fname[strlen(fname) - 1] = '\0';
        fptr1 = fopen(fname, "r");
        if (!fptr1) {
                printf("Unable to open the input file!!\n");
                return 0;
                    }
        printf("Content of the file: \n\n");
        while ((str = getc(fptr1)) != EOF)
        putchar(str);

        fptr2 = fopen(temp, "w");
        if (!fptr2)
        {
                printf("Unable to open a temporary file to write!!\n");
                fclose(fptr1);
                return 0;
        }

        printf(" Input the content of the new line : ");
        fgets(newln, MAX, stdin);

        printf(" Input the line no you want to replace : ");
        scanf("%d", &lno);
        lno++;
        rewind(fptr1);
        while ((fgets(str, MAX, fptr1))!=NULL)
        {
                linectr++;
                if (linectr == lno)
                        fputs(newln, fptr2);
                    else
                        fputs(str, fptr2);
        }
        fclose(fptr1);
        fclose(fptr2);
        remove(fname);
        rename(temp, fname);
        printf(" Replacement did successfully \n");
        return 0;
  }

What I have tried:

I have tried understanding different programs with same fault but didn't get clear view.
I have been trying to change the code but its not working completely, as of now it is working partially.