Functionpointers.cpp

#include<iostream>
#define maxi 100

using namespace std;

int flag;

float add(float a,float b){
    return (a+b);
}

float sub(float a,float b){
    return (a-b);
}

float mul(float a,float b){
    return (a*b);
}

float div(float a,float b){
    if(b==0){
        cout<<"Not Possible";
        flag=1;
        return -1;
    }
    return (a/b);
}

float calc(float a,float b,float(*fnptr)(float a,float b)){
    return fnptr(a,b);
}

int main()
{
    int ch,ch2;
    float a,b;
    cout<<"Choice : 1) Illustrating Function Pointers 2) Illustrating Pointer to Array 3) Illustrating pointer to String 4) Exit :P";
    while(1){
        cout<<"\nEnter your choice...";
        cin>>ch;
        if(ch==1){
            cout<<"Choice : 1)Add 2)Subtract 3)Multiply 4)Divide";
            cout<<"\nEnter the choice for calculation...";
            cin>>ch2;
            if(ch2==1){
                cout<<"Enter any two numbers...";
                cin>>a>>b;
                cout<<"The result is "<<calc(a,b,add);
            }
            else if(ch2==2){
                cout<<"Enter any two numbers...";
                cin>>a>>b;
                cout<<"The result is "<<calc(a,b,sub);
            }
            else if(ch2==3){
                cout<<"Enter any two numbers...";
                cin>>a>>b;
                cout<<"The result is "<<calc(a,b,mul);
            }
            else if(ch2==4){
                cout<<"Enter any two numbers...";
                cin>>a>>b;
                flag=0;
                if(calc(a,b,div)!=-1 || flag==0){
                    cout<<"The result is "<<calc(a,b,div);
                }
            }
        }
        else if(ch==2){
            int n,i;
            cout<<"Enter the number of elements of the array..";
            cin>>n;

            int a[n];
            cout<<"Enter the elements one by one..";
            for(i=0;i<n;i++){
                cin>>a[i];
            }

            int *ptr;
            ptr=a;
            cout<<"The elements of the array is..";
            for(i=0;i<n;i++){
                cout<<*ptr<<" ";
                ptr++;
            }
        }
        else if(ch==3){
            char s[maxi];
            cout<<"Enter any string..";
            cin>>s;
            char *ptr;
            ptr=s;
            cout<<"The String is..";
            while(*ptr!='\0'){
                cout<<*ptr;
                ptr++;
            }
        }
        else{
            break;
        }
    }
    return 0;
}