Question:C code to print or display lower triangular matrix 

#include<stdio.h>
int main(){
  int a[3][3],i,j;
  float determinant=0;

  printf("Enter the 9 elements of matrix: ");
  for(i=0;i<3;i++)
      for(j=0;j<3;j++)
           scanf("%d",&a[i][j]);

  printf("\nThe matrix is\n");
  for(i=0;i<3;i++){
      printf("\n");
      for(j=0;j<3;j++)
           printf("%d\t",a[i][j]);
  }

   printf("\nSetting zero in upper triangular matrix\n");
   for(i=0;i<3;i++){
      printf("\n");
      for(j=0;j<3;j++)
           if(i<=j)
             printf("%d\t",a[i][j]);
           else
             printf("%d\t",0);
  }


   return 0;
}
Sample Output:
Enter the 9 elements of matrix: 1
2
3
4
5
6
7
8
9

The matrix is

1       2       3
4       5       6
7       8       9
Setting zero in upper triangular matrix

1       2       3
0       5       6
0       0       9

Question:C code to print or display upper triangular matrix 

#include<stdio.h>
int main(){
  int a[3][3],i,j;
  float determinant=0;

  printf("Enter the 9 elements of matrix: ");
  for(i=0;i<3;i++)
      for(j=0;j<3;j++)
           scanf("%d",&a[i][j]);

  printf("\nThe matrix is\n");
  for(i=0;i<3;i++){
      printf("\n");
      for(j=0;j<3;j++)
           printf("%d\t",a[i][j]);
  }

   printf("\nSetting zero in upper triangular matrix\n");
   for(i=0;i<3;i++){
      printf("\n");
      for(j=0;j<3;j++)
           if(i>=j)
             printf("%d\t",a[i][j]);
           else
             printf("%d\t",0);
  }


   return 0;
}
Sample output:
Enter the 9 elements of matrix: 1
2
3
4
5
6
7
8
9

The matrix is

1       2       3
4       5       6
7       8       9
Setting zero in upper triangular matrix

1       0       0
4       5       0
7       8       9

Question:C code of two 2 by 2 matrix multiplication using Strassen algorithm 

#include<stdio.h>
int main(){
  int a[2][2],b[2][2],c[2][2],i,j;
  int m1,m2,m3,m4,m5,m6,m7;

  printf("Enter the 4 elements of first matrix: ");
  for(i=0;i<2;i++)
      for(j=0;j<2;j++)
           scanf("%d",&a[i][j]);

  printf("Enter the 4 elements of second matrix: ");
  for(i=0;i<2;i++)
      for(j=0;j<2;j++)
           scanf("%d",&b[i][j]);

  printf("\nThe first matrix is\n");
  for(i=0;i<2;i++){
      printf("\n");
      for(j=0;j<2;j++)
           printf("%d\t",a[i][j]);
  }

  printf("\nThe second matrix is\n");
  for(i=0;i<2;i++){
      printf("\n");
      for(j=0;j<2;j++)
           printf("%d\t",b[i][j]);
  }

  m1= (a[0][0] + a[1][1])*(b[0][0]+b[1][1]);
  m2= (a[1][0]+a[1][1])*b[0][0];
  m3= a[0][0]*(b[0][1]-b[1][1]);
  m4= a[1][1]*(b[1][0]-b[0][0]);
  m5= (a[0][0]+a[0][1])*b[1][1];
  m6= (a[1][0]-a[0][0])*(b[0][0]+b[0][1]);
  m7= (a[0][1]-a[1][1])*(b[1][0]+b[1][1]);

  c[0][0]=m1+m4-m5+m7;
  c[0][1]=m3+m5;
  c[1][0]=m2+m4;
  c[1][1]=m1-m2+m3+m6;

   printf("\nAfter multiplication using \n");
   for(i=0;i<2;i++){
      printf("\n");
      for(j=0;j<2;j++)
           printf("%d\t",c[i][j]);
   }

   return 0;
}
Sample output:
Enter the 4 elements of first matrix: 1
2
3
4
Enter the 4 elements of second matrix: 5
6
7
8

The first matrix is

1       2
3       4
The second matrix is

5       6
7       8
After multiplication using

19      22
43      50

Question:C program to calculate determinant of a matrix 

#include<stdio.h>
int main(){
  int a[3][3],i,j;
  int determinant=0;

  printf("Enter the 9 elements of matrix: ");
  for(i=0;i<3;i++)
      for(j=0;j<3;j++)
           scanf("%d",&a[i][j]);

  printf("\nThe First matrix is\n");
  for(i=0;i<3;i++){
      printf("\n");
      for(j=0;j<3;j++)
           printf("%d\t",a[i][j]);
  }

  for(i=0;i<3;i++)
      determinant = determinant + (a[0][i]*(a[1][(i+1)%3]*a[2][(i+2)%3] - a[1][(i+2)%3]*a[2][(i+1)%3]));

  printf("\nDeterminant of matrix is: %d",determinant);

   return 0;
}

Question:C code for Determinant of 2X2 matrix 

#include<stdio.h>
int main(){
  int a[2][2],i,j;
  long determinant;

  printf("Enter the 4 elements of matrix: ");
  for(i=0;i<2;i++)
      for(j=0;j<2;j++)
           scanf("%d",&a[i][j]);

  printf("\nThe matrix is\n");
  for(i=0;i<2;i++){
      printf("\n");
      for(j=0;j<2;j++)
           printf("%d\t",a[i][j]);
  }

  determinant = a[0][0]*a[1][1] - a[1][0]*a[0][1];

  printf("\nDeterminant of 2X2 matrix: %ld",determinant);
 
   return 0;
}
Sample Output:
Enter the 4 elements of matrix: 4
8
3
9

The matrix is

4       8
3       9

Determinant of 2X2 matrix: 12

Question:C code for Determinant of 3X3 matrix 

#include<stdio.h>

int main(){

  int a[3][3],i,j;

  long determinant;



  printf("Enter the 9 elements of matrix: ");
  for(i=0;i<3;i++)
      for(j=0;j<3;j++)
           scanf("%d",&a[i][j]);

  printf("\nThe matrix is\n");
  for(i=0;i<3;i++){
      printf("\n");
      for(j=0;j<3;j++)
           printf("%d\t",a[i][j]);
  }

  determinant = a[0][0]*((a[1][1]*a[2][2]) - (a[2][1]*a[1][2])) -a[0][1]*(a[1][0]*a[2][2] - a[2][0]*a[1][2]) + a[0][2]*(a[1][0]*a[2][1] - a[2][0]*a[1][1]);

  printf("\nDeterminant of 3X3 matrix: %ld",determinant);
 
   return 0;
}
Sample output:
Enter the 9 elements of matrix: 1
2
3
4
5
6
7
8
9

The matrix is

1       2       3
4       5       6
7       8       9

Determinant of 3X3 matrix: 0

Question:C program to write to a file 

#include<stdio.h>
int main(){
FILE *fp;
char ch;
fp=fopen("file.txt","w");
printf("\nEnter data to be stored in to the file:");
while((ch=getchar())!=EOF)
putc(ch,fp);
fclose(fp);
return 0;
}

Question:COPY DATA FROM ONE FILE TO ANOTHER FILE USING C PROGRAM 

#include<stdio.h>
int main(){
  FILE *p,*q;
  char file1[20],file2[20];
  char ch;
  printf("\nEnter the source file name to be copied:");
  gets(file1);
  p=fopen(file1,"r");
  if(p==NULL){
      printf("cannot open %s",file1);
      exit(0);
  }
  printf("\nEnter the destination file name:");
  gets(file2);
  q=fopen(file2,"w");
  if(q==NULL){
      printf("cannot open %s",file2);
      exit(0);
  }
  while((ch=getc(p))!=EOF)
      putc(ch,q);
  printf("\nCOMPLETED");
  fclose(p);
  fclose(q);
 return 0;
}

Question:DISPLAY SOURCE CODE AS OUTPUT IN C PROGRAM 

#include<stdio.h>
int main(){
    FILE *p;
    char ch;
    p=fopen("raja.c","r");
    while((ch=getc(p))!=-1)
         putchar(ch);
    fclose(p);
    return 0;
}

Question:How to read a text file by c program 

#include<stdio.h>
int main(){
char str[70];
FILE *p;
if((p=fopen("string.txt","r"))==NULL){
printf("\nUnable t open file string.txt");
exit(1);
}
while(fgets(str,70,p)!=NULL)
puts(str);
fclose(p);
return 0;
}