10th Assignment Solution

1. Here's the main function of a program that  
    • Reads in two matrices by prompting the user for their dimensions, dynamically allocating 
      memory from the heap, and reading the values into the memory using row major ordering 
      for the matrix values (1%). 
    • Multiplies the two matrices together and puts the result into another dynamically 
      allocated piece of memory (after checking that the dimensions are appropriate for matric 
      multiplication) (1%). 
    • Outputs the two input and the result matrices (0.5%). 
Write the implementations of the functions input_matrix, matrix_multiply, 
and output_matrix (2.5%). 
/*---------------------------------------------------------------------------*/ 
int main(void) { 
 
    double *m1,*m2,*m3; 
    int m1_rows,m1_columns,m2_rows,m2_columns; 
 
    if (((m1 = input_matrix(&m1_rows,&m1_columns,"Matrix 1")) != NULL) && 
((m2 = input_matrix(&m2_rows,&m2_columns,"Matrix 2")) != NULL) && 
((m3 = malloc(m1_rows*m2_columns*sizeof(double))) != NULL)) { 
        printf("Matrix 1\n"); 
        output_matrix(m1,m1_rows,m1_columns); 
        printf("Matrix 2\n"); 
        output_matrix(m2,m2_rows,m2_columns); 
        if (matrix_multiply(m1,m1_rows,m1_columns,m2,m2_rows,m2_columns,m3)) 
{ 
            printf("Product\n"); 
            output_matrix(m3,m1_rows,m2_columns); 
            free(m1); 
            free(m2); 
            free(m3); 
            return(0); 
        } else { 
            printf("Error in dimensions\n"); 
            free(m1); 
            free(m2); 
            free(m3); 
            return(-1); 
        } 
    } else { 
        free(m1); 
        free(m2); 
        free(m3); 
        printf("Error allocating memory\n"); 
        return(-2); 
    } 
} 
 
  
 
2. Since we talked about pointers, memory allocation and linked lists in class, I'd like you to 
   write a program that allows the user to: 
    • Enter the names of persons (1%) 
    • For each person entered, enter the name of his/her best buddy (1%) 
    • Print out the "best buddys" (0.5%) 
    •  Each person's name entered must be stored in a node of a linked list. 
    •  Each node of the linked list must contain (only) the persons name, a pointer to the node for its 
       best buddy, and a pointer to the next node in the list. 
    •  Before the program completes it must explicitly free the malloced memory. 
    
Here what a sample run should look like (with the user input shown in italics) ... 
Enter nation name : Tom 
 
Enter nation name : Betty 
 
Enter nation name : Martin 
 
Enter nation name : Michael 
 
Enter nation name : Amanda 
 
Enter nation name : Catharine 
 
Enter nation name : 
 
Enter best ally name for Catharine : Amanda 
 
Enter best ally name for Amanda : Michael 
 
Enter best ally name for Michael : Martin 
 
Enter best ally name for Martin : Betty 
 
Enter best ally name for Betty : Amanda 
 
Enter best ally name for Tom : Catharine 
 
The best ally of Catharine is Amanda 
 
The best ally of Amanda is Michael 
 
The best ally of Michael is Martin 
 
The best ally of Martin is Betty 
 
The best ally of Betty is Amanda 
 
The best ally of Tom is Catharine 


Remarks:
• The assignment is due next Friday, Nov. 19th, 11:59PM. 
• You need to submit two (matrix.c, best_buddies.c) file with the corresponding C code using submit2 
  (Please DO NOT submit compiled executables)! Furthermore, the C code needs to compile w/o warnings using -Wall (otherwise the TA's won't look at it) a