C program to File to upper case using command line arguments

Below is C program to File to upper case using command line arguments .

Program:

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/* 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; }