Question

In c programming, I need to write a program that reverses each of the lines in a file.

The program accepts two command line arguments:

• The first one is the name of the input file
• The second is the name of the output file

If the user didn't give two filenames, display an error message and exit.

The program reads in each line of the input file and writes each line in reverse to the output file.

Note, the lines should be in the same order, but each line is reversed, (words are written backwards).

Indicate how many characters there are in the file and how many lines if possible.

Answer 1

C code

==================================================================

#include<stdio.h>
#include<string.h>
#define MAXCHAR 1000

//reverse a string
void stringrev(char s[],int len)
{
int i=0;
int j=len-1;
char temp;
while(i < j) {
    temp = s[i];
    s[i++] = s[j];
    s[j--] = temp;
}
}

int main(int argc, char** argv)
{
   FILE *f1,*f2;
   char str[MAXCHAR];
   int line=0,count=0,k;

//check for 3 arguements
if(argc!=3)
{
printf("you have not given enough arguments\n");
return -1;
}

   // open file for reading
f1 = fopen(argv[1], "r");
//open file for writing
f2 = fopen(argv[2], "w");
//if input file exists
if (f1 != NULL ) {
  
    //printf("File open successfully!\n");
    while (fgets(str, MAXCHAR, f1) != NULL)
   {
         printf("%s", str);
       k=strlen(str);
   //count character
         count=count+k;
   //reverse string
        stringrev(str,k);
   //write to file
       fputs(str, f2);
       line++;    
   }
    printf("lines are: %d\ntotal character are: %d\n",line,count);
  
}
else {
    printf("ERROR:File not found.\n");
    return -1;
}


// close connection
fclose(f1);
fclose(f2);
  

return 0;
}

==================================================================

Output