Here is source code of the C Program to delete a specific line from a text file. The C program is successfully compiled and run on a Linux system. The program output is also shown below.

/*
* C Program Delete a specific Line from a Text File
*/
#include <stdio.h>

int main()
{
FILE *fileptr1, *fileptr2;
char filename[40];
char ch;
int delete_line, temp = 1;

printf("Enter file name: ");
scanf("%s", filename);
//open file in read mode
fileptr1 = fopen(filename, "r");
ch = getc(fileptr1);
` while (ch != EOF)
{
printf("%c", ch);
ch = getc(fileptr1);
}
//rewind
rewind(fileptr1);
printf(" \n Enter line number of the line to be deleted:");
scanf("%d", &delete_line);
//open new file in write mode
fileptr2 = fopen("replica.c", "w");
ch = getc(fileptr1);
while (ch != EOF)
{
ch = getc(fileptr1);
if (ch == '\n')
temp++;
//except the line to be deleted
if (temp != delete_line)
{
//copy all lines in file replica.c
putc(ch, fileptr2);
}
}
fclose(fileptr1);
fclose(fileptr2);
remove(filename);
//rename the file replica.c to original name
rename("replica.c", filename);
printf("\n The contents of file after being modified are as follows:\n");
fileptr1 = fopen(filename, "r");
ch = getc(fileptr1);
while (ch != EOF)
{
printf("%c", ch);
ch = getc(fileptr1);
}
fclose(fileptr1);
return 0;
}



$ cc pgm47.c
$ a.out
Enter file name: pgm1.c
/*
* C PROGRAM TO CONVERSION FROM Decimal to hexadecimal
*/

#include<stdio.h>
int main()
{
long int decimalnum, remainder, quotient;
int i = 1, j, temp;
char hexadecimalnum[100];

printf("Enter any decimal number: ");
scanf("%ld", &decimalnum);

quotient = decimalnum;

while (quotient != 0)
{
temp = quotient % 16;
//To convert integer into character
if (temp < 10)
temp = temp + 48;
else
temp = temp + 55;

hexadecimalnum[i++] = temp;
quotient = quotient / 16;
}

printf("Equivalent hexadecimal value of decimal number %d: ", decimalnum);
for (j = i - 1; j > 0; j--)
printf("%c", hexadecimalnum[j]);
return 0;
}


Enter line number of the line to be deleted: 10

The contents of file after being modified are as follows:
*
* C PROGRAM TO CONVERSION FROM Decimal to hexadecimal
*/

#include<stdio.h>
int main()
{
long int decimalnum, remainder, quotient;
int i = 1, j, temp;

printf("Enter any decimal number: ");
scanf("%ld", &decimalnum);

quotient = decimalnum;

while (quotient != 0)
{
temp = quotient % 16;
//To convert integer into character
if (temp < 10)
temp = temp + 48;
else
temp = temp + 55;

hexadecimalnum[i++] = temp;
quotient = quotient / 16;
}

printf("Equivalent hexadecimal value of decimal number %d: ", decimalnum);
for (j = i - 1; j > 0; j--)
printf("%c", hexadecimalnum[j]);
return 0;
}