C Exercises: Delete a specific line from a file
C File Handling : Exercise-8 with Solution
Write a program in C to delete a specific line from a file.
Assume that the content of the file test.txt is : test line 1 test line 2 test line 3 test line 4
Sample Solution:
C Code:
#include <stdio.h>
#include <string.h>
#define MAX 256
int main()
{
int lno, ctr = 0;
char ch;
FILE *fptr1, *fptr2;
char fname[MAX];
char str[MAX], temp[] = "temp.txt";
printf("\n\n Delete a specific line from a file :\n");
printf("-----------------------------------------\n");
printf(" Input the file name to be opened : ");
scanf("%s",fname);
fptr1 = fopen(fname, "r");
if (!fptr1)
{
printf(" File not found or unable to open the input file!!\n");
return 0;
}
fptr2 = fopen(temp, "w"); // open the temporary file in write mode
if (!fptr2)
{
printf("Unable to open a temporary file to write!!\n");
fclose(fptr1);
return 0;
}
printf(" Input the line you want to remove : ");
scanf("%d", &lno);
lno++;
// copy all contents to the temporary file except the specific line
while (!feof(fptr1))
{
strcpy(str, "\0");
fgets(str, MAX, fptr1);
if (!feof(fptr1))
{
ctr++;
/* skip the line at given line number */
if (ctr != lno)
{
fprintf(fptr2, "%s", str);
}
}
}
fclose(fptr1);
fclose(fptr2);
remove(fname); // remove the original file
rename(temp, fname); // rename the temporary file to original name
/*------ Read the file ----------------*/
fptr1=fopen(fname,"r");
ch=fgetc(fptr1);
printf(" Now the content of the file %s is : \n",fname);
while(ch!=EOF)
{
printf("%c",ch);
ch=fgetc(fptr1);
}
fclose(fptr1);
/*------- End of reading ---------------*/
return 0;
}
Sample Output:
Delete a specific line from a file : ----------------------------------------- Input the file name to be opened : test.txt Input the line you want to remove : 2 Now the content of the file test.txt are : test line 1 test line 3 test line 4
Flowchart:

C Programming Code Editor:
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Next: Write a program in C to replace a specific line with another text in a file.
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C Programming: Tips of the Day
What is the size of an enum in c?
An enum is only guaranteed to be large enough to hold int values. The compiler is free to choose the actual type used based on the enumeration constants defined so it can choose a smaller type if it can represent the values you define. If you need enumeration constants that don't fit into an int you will need to use compiler-specific extensions to do so.
Ref : https://bit.ly/3ypg4k8
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