File Copy using command line arguments

/* File Copy using command line arguments */

#include<stdio.h>
int main(int argc,char *argv[])
{
 FILE *fs,*ft;
 int ch;
 if(argc!=3)
 {
  printf("Invalide numbers of arguments.");
  return 1;
 }
 fs=fopen(argv[1],"r");
 if(fs==NULL)
 {
  printf("Can't find the source file.");
  return 1;
 }
 ft=fopen(argv[2],"w");
 if(ft==NULL)
 {
  printf("Can't open target file.");
  fclose(fs);
  return 1;
 }

 while(1)
 {
  ch=fgetc(fs);
  if (feof(fs)) break;
  fputc(ch,ft);
 }

 fclose(fs);
 fclose(ft);
 return 0;
}

File to upper case using command line arguments

/* File to upper case using command line arguments */

#include<stdio.h>
int main(int n,char *a[])
{
 int c;
 FILE *fr,*fw;

 if(n!=3)
 {
  printf("Invalide numbers of arguments.");
  return 1;
 }

 if((fr=fopen(a[1],"r"))==NULL)
 {
  printf("File can't be open.");
  return 1;
 }
 if((fw=fopen(a[2],"r+"))==NULL)
 {
  printf("File can't be open.");
  fclose(fr);
  return 1;
 }
 while(1)
 {
  c=fgetc(fr);
  if(feof(fr)) break;
  c=~c;
  fputc(c,fw);
 }
 fclose(fr);
 fclose(fw);
 return 0;
}

Count characters of file

/* Count characters of file */

#include<stdio.h>
int main()
{
 FILE *fp;
 char a[10];
 long cnt=0;
 int c;

 printf("Type a file name : ");
 gets(a);
 
 if((fp=fopen(a,"r"))==NULL)
  printf("File dosen't exist.");
 else
 {
  while(1)
  {
   c=fgetc(fp);
   if(feof(fp)) break;
   cnt++;
  }
  printf("\nfile have %ld characters",cnt);
 }
 fclose(fp);
 return 0;
}

Write to text file

/* Write to text file */

#include<stdio.h>
int main()
{
 FILE *fp;
 char mystr[100];

 fp=fopen("mytext.txt","w");
 if(fp==NULL)
 {
  puts("Some error occured.");
  return 1;
 }

 printf("\nEnter some lines:\n");
 while(strlen(gets(mystr))>0)
 {
  fputs(mystr,fp);
  fputs("\n",fp);
 }
 fclose(fp);
 return 0;
}

Read text file

/* Read text file */

#include<stdio.h>
int main()
{
 FILE *fp;
 int ch;
 
 fp=fopen("myfile.txt","r");
 if(fp==NULL)
 {
  printf("Can't find the source file.");
  return 1;
 } 
 while(1)
 {
  ch=fgetc(fp);
  if(feof(fp)) break;
  printf("%c",ch);
 } 
 fclose(fp);
 return 0;
}