Question:Writing of entire array to a file using c program 

#include<stdio.h>
int main(){
  FILE *p;
  int i,a[10];
  if((p=fopen("myfile.dat","wb"))==NULL){
      printf("\nUnable to open file myfile.dat");
      exit(1);
  }
  printf("\nEnter ten values, one value on each line\n");
  for(i=0;i<10;i++)
      scanf("%d",&a[i]);
  fwrite(a,sizeof(a),1,p);
  fclose(p);
  return 0;
}

Question:Concatenate many files and store them in a file in c programming language 

#include<stdio.h>
 void concatenate(FILE *fp1,FILE *fp2,char *argv[],int argc);
 int main(int argc,char *argv[]){
   FILE *fp1,*fp2;
   concatenate(fp1,fp2,argv,argc);
   return 0;
 }

void concatenate(FILE *fp1,FILE *fp2,char **argv,int argc){
   int i,ch;
   fp2=fopen("files","a");
   for(i=1;i<argc-1;i++){
      fp1=fopen(argv[i],"r");
      while((ch=getc(fp1))!=EOF)
      putc(ch,fp2);
   }
 }

Question:C program to get total file  size 

#include <time.h>
#include <sys\stat.h>
#include <stdio.h>
void main()
{
    struct stat status;
    FILE *fp;
    fp=fopen("test.txt","r");
    fstat(fileno(fp),&status);
    clrscr();
    printf("Size of file : %d",status.st_size);
    printf("Drive name   : %c",65+status.st_dev);
    getch();
}

Question:Write a c program to know given file is regular file, character special or it is directory? 

#include "time.h"
#include "sys\stat.h"
#include "stdio.h"
void main(){
    struct stat status;
    FILE *fp;
    stat("c:\\tc\\bin",&status);
    clrscr();
    if (status.st_mode & S_IFDIR)
         printf("It is directory.\n");
    if (status.st_mode & S_IFCHR)
         printf("It is chracter file.");
    if (status.st_mode & S_IFREG)
         printf("It is reggular file.");
    getch();
}
Output: It is directory.

Question:Write a c program to know read/write permission of given file. 

#include "time.h"
#include "sys\stat.h"
#include "stdio.h"
void main(){
    struct stat status;
    FILE *fp;
    stat("test.txt",&status);
    clrscr();
    if (status.st_mode & S_IREAD)
         printf("You have read permission.\n");
    if (status.st_mode & S_IWRITE)
         printf("You have write permission.");
    getch();

}

Question:Write a c program to know the last date of modification of any file 

#include "time.h"
#include "sys\stat.h"
#include "stdio.h"
int main(){
    struct stat status;
    FILE *fp;
    fp=fopen("test.txt","r");
    fstat(fileno(fp),&status);
    
    printf("Last date of modification : %s",ctime(&status.st_ctime));
    return 0;
}

Question:Write a c program to find out the size and drive where file has stored of any given file? 

#include "time.h"
#include "sys\stat.h"
#include "stdio.h"
int main(){
    struct stat status;
    FILE *fp;
    fp=fopen("test.txt","r");
    fstat(fileno(fp),&status);
    printf("Size of file : %d",status.st_size);
    printf("Drive name   : %c",65+status.st_dev);
    return 0;
}

Question:How to use complex numbers in c 

#include<stdio.h>
int main(){
int a,b;

printf("Enter any complex number in the format a+ib: ");
scanf("%d+i%d",&a,&b);

printf("Real part is: %d",a );
printf("\nImaginary part is: %d",b);

return 0;

}

Question:C program to printf complex numbers 

#include<stdio.h>
int main(){
int a,b;

printf("Enter the real part of complex number: ");
scanf("%d",&a);

printf("Enter the imaginary part of complex number: ");
scanf("%d",&b);

printf("\nComplex number is: %d%+di",a,b );

return 0;

}

Question:C program to add two complex numbers 

#include<stdio.h>
int main(){
  int a,b,c,d,x,y;
  printf("\nEnter the first complex number:");
  scanf("%d%d",&a,&b);
  printf("\nEnter the second complex number:");
  scanf("%d%d",&c,&d);
  if(b<0)
      printf("%d-i\n",a-b);
  else
      printf("d+i\n",a+b);
  if(d<0)
      printf("d-i\n",c-d);
  else
      printf("%d+i\n",c+d);
  printf("\nADDITION ");
  x=a+c;
  y=b+d;
  if(y>0)
      printf("%d-i%d",x,-y);
  else
      printf("%d+i%d",x,+y);
  printf("\n\nSUBTRACTION ");
  x=a-c;
  y=b-d;
  if(y<0)
      printf("%d-i%d",x,-y);
  else
      printf("%d+i%d",x,+y);
  return 0;
}