C

Problem 01

“Hello World!” in C

This challenges requires you to print Hello, World! on a single line, and then print the already provided input string to stdout.

Example: s = "Life is beautiful"

Output

Hello, World!
Life is beautiful

Solution

#include <stdio.h>

int main() {
    char s[100];
    scanf("%[^\n]%*c", &s);
    printf("Hello, World!\n");
    printf("%s",s);    
    return 0;
}

Problem 02

Playing with Characters

You have to print the character ch, in the first line. Then print s in next line. In the last line print the sentence sen.

Input format - take a character, ch as input - take the string, s as input - take the sentence sen as input

Example

C
Language
Welcome To C!!

Solution

#include <stdio.h>

int main() 
{
    char ch;
    char s[100];
    char sen[100];
    
    scanf("%c",&ch);
    scanf("%s",&s);
    getchar();
    scanf("%[^\n]%*c", sen);

    printf("%c\n",ch);
    printf("%s\n",s);
    printf("%s\n",sen);
    return 0;
}

Problem 03

Sum and Difference of Two Numbers

Your task is to take two numbers of int data type, two numbers of float data type as input and output their sum:

1. Declare 4 variables: two of type int and two of type float
2. Read 2 lines of input stdin and initialize your 4 variables
3. Use the + and - operator to perfom the following operations:
   • Print the sum and difference of two int variable on a new line.
   • Print the sum and difference of two float variable rounded to one decimal place on a new line.

Solution

int main()
{
    int a;
    int b;
    float c;
    float d;

    scanf("%d", &a);
    scanf("%d", &b);
    scanf("%f", &c);
    scanf("%f", &d); 

    printf("%d %d\n" , a+b, a-b);
    printf("%.1f %.1f\n" , c+d, c-d);
    return 0;
}

Problem 04

Functions in C

Write a function:

• int max_of_four(int a, int b, int c, int d)

which reads four arguments and returns the greatest of them

Solution

int max_of_four(int a, int b, int c, int d) {
    int max = 0;
    int list[4] = {a, b, c, d};
    for(int i=0; i<4; i++) {
        if(max < list[i]) {
            max = list[i];
    }
  }
  return max;    
}

int main() {
  int a, b, c, d;
  scanf("%d %d %d %d", &a, &b, &c, &d);
  int ans = max_of_four(a, b, c, d);
  printf("%d", ans);
  return 0;
}

Problem 05

Pointers in C

Complete the function:

• void update(int *a, int *b)

It receives two integer pointers, int *a and int *b. Set the value of a to their sum, and b to their absolute difference. There is no return value, and no return statement is needed

• \(a' = a +b\)
• \(b' = |a - b|\)

Solution

#include <stdio.h>

void update(int *a,int *b) {
    int sum;
    int dif;

    sum = *a + *b;
    dif = *a - *b;
    if(dif < 0) {
        dif = -dif;
    }
    *a = sum;
    *b = dif;
}

int main() {
    int a, b;
    int *pa = &a, *pb = &b;

    scanf("%d %d", &a, &b);
    update(pa, pb);
    printf("%d\n%d", a, b);
    return 0;
}