Question

c program

Your teacher want to find out who is the most hardworking student in class! They want to input the names according to the order they fell asleep, then print their names in the reverse order. Although you can create an array large enough to store all names, your teacher don’t want to waste our precious memory! The first line of the input is an integer x, which indicate the number of students in class. Then there are x lines of strings. Each line corresponds to a student’s name. Assume a name is at most 14 characters. Task 1: Read the students’ names from user input and pass the data to your teacher’ function. You are requested to create an array with x strings. Your teacher have given you the skeleton code. Please complete the main function to achieve your task. #include <stdio.h> #include <stdlib.h> #include <string.h> void foo(char **names, int x) { int i; for (i = x - 1; i >= 0; i--)      printf(“%s\n”, names[i]); } int main(void) { // write your codes here (use fgets() to read input, why??) foo(names, x); // write your codes here return 0; } Sample Input: 3 George Bush Bill Gates Steve Jobs Sample Output: Steve Jobs Bill Gates George Bush Your teacher suddenly realized that the lecture has covered “structure”! So they says: “Let’s change the code and use structure!” Task 2: You task is the same, but your teacher have given you another (terrible) skeleton code below. Please complete the main function to achieve your task. #include <stdio.h> #include <stdlib.h> #include <string.h> typedef struct { int no; char(*names)[16]; } myList; void foo(myList *bar) { int i; for (i = bar->no - 1; i >= 0; i--)      printf(“%s\n”, bar->names[i]); } int main(void) { // write your codes here foo(bar); // write your codes here return 0; } One of your (annoying) teacher says: “I don’t like the design of the structure ._.” Task 3: You are given another structure declaration below. Complete the same task as in Task 2. typedef struct { int no; char names[][16]; } myList;

Problem 2 (Memory Layout):

Run the following code snippets using the online compiler or VS, what do you expect? #include <stdio.h> int hi(void) {} int main(void) { printf("Hello\n"); int a = hi(); printf("%d\n", a); } Explain the output.

Answer 1

Please find the code below:

Part one

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

void foo(char **names, int x)

{
   int i;
   for (i = x - 1; i >= 0; i--)
       printf("%s ", names[i]);

}

int main(void)

{

   // write your codes here (use fgets() to read input, why??)
   printf("Enter number of students : ");
   int x;
   scanf("%d",&x);

   getch();
   char** names;
   names= (char **)malloc(x* sizeof(char*));
   int i;
   for(i=0;i<x;i++){
       names[i] = (char *)malloc(14* sizeof(char));
   }
   fgets(names[0], 14, stdin); //ingore extra line
   for(i=0;i<x;i++){
       fgets(names[i], 14, stdin);
   }

   foo(names, x);

   // write your codes here

   return 0;

}

output:

Part Two

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

typedef struct {

   int no;

   char(*names)[16];

} myList;

void foo(myList *bar)

{

   int i;

   for (i = bar->no - 1; i >= 0; i--)

       printf("%s ", bar->names[i]);

}

int main(void)

{

   // write your codes here (use fgets() to read input, why??)
   printf("Enter number of students : ");
   myList *bar;
   bar = (myList *)malloc(1* sizeof(myList));
   scanf("%d",&(bar->no));
  
bar->names= (char **)malloc(bar->no* sizeof(char*));

   fgets(bar->names[0], 16, stdin); //ingore extra line

   // write your codes here
   int i;
   for(i=0;i<bar->no;i++){
       fgets(bar->names[i], 16, stdin);
   }

   foo(bar);

   // write your codes here

   return 0;

}

output:

Part Three

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

typedef struct {

   int no;

   char names[][16];

} myList;

void foo(myList *bar)

{

   int i;

   for (i = bar->no - 1; i >= 0; i--)

       printf("%s ", bar->names[i]);

}

int main(void)

{

   // write your codes here (use fgets() to read input, why??)
   printf("Enter number of students : ");
   myList *bar;
   bar = (myList *)malloc(1* sizeof(myList));
   scanf("%d",&(bar->no));

   fgets(bar->names[0], 16, stdin); //ingore extra line

   // write your codes here
   int i;
   for(i=0;i<bar->no;i++){
       fgets(bar->names[i], 16, stdin);
   }

   foo(bar);

   // write your codes here

   return 0;

}

output:

On running code:

#include <stdio.h>

int hi(void) {}

int main(void)

{

printf("Hello ");

int a = hi();

printf("%d ", a);

}

getting below output: