Codefest

Problem 1:Multipurpose

Time limit: 2 secs

Perform the following operations:
1. Find the square of a number
2. Find the product of two numbers
3. Find the summation of three numbers
4. Concatenate two strings

Input :

Each line contains a input test-case. First integer, m, in every line denotes the operation to be performed, followed by the integers or strings needed for the operation:
m=1 for finding the square of the followed integer.
m=2 for finding the product of followed two integers.
m=3 for finding the summation of followed three integers.
m=4 for concatenating two strings

Output :

For each line in the input, output the required result.

Constraints :

Number of test cases are less than 30 1<=m<=4
Remaining integers will be from 1 to 1000, inclusive.
Strings will contain only upper and lower case alphabets and will be of length less than 30.

Sample Input :

1 2
2 2 3
3 3 4 5
4 Code Fest

Sample Output :

4
6
12
CodeFest

Score :

USE OF FUNCTIONS IN "math.h" IS NOT ALLOWED
I = Number of if, else, switch, ternary
B = Number of bitwise operators ( ~, |, &, ^, >>, << )
K = Number of keywords
C = Number of parentheses '(' ')' and number of semicolons ';'
A = Number of logical operators ( &&, ||)
L = Number of loops ( for, while, do), goto

Solution:

Function Pointers are pointers, i.e. variables, which point to the address of a function. This is useful because functions encapsulate behavior. For instance, every time you need a particular behavior such as drawing a line, instead of writing out a bunch of code, all you need to do is call the function.
In the given problem there are four different operations to be performed. First of all we make 4 functions having same prototype, so that we can make an array of function pointers. Now we call the required function in accordance to the given input. This makes the proper use of function pointer, and reduces the use of conditional statements.

Reference:5.11 Pointers to Functions, Dennis Ritchie

Code:

u,x,y,z;
G()
{}
H()
{
	scanf("%d",&x);
	printf("%d\n",x*x);
}

I()
{
	scanf("%d%d",&x,&y);
	printf("%d\n",x*y);
}
J()
{
	scanf("%d%d%d",&x, &y, &z);
	printf("%d\n",x+y+z);
}
K()
{
	char a[30],b[30];
	scanf("%s%s",a,b);
	printf("%s%s\n",a,b);
}
(*p[5])() = {G,H,I,J,K};
main(o)
{
       (scanf("%d",&o)+1)&&( p[o](), main());
}

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