c program to check entered number by user-CodePudding

I am new to programming, started with C quite recently and I use CLion IDE.

I need to solve something, but I am not sure how exactly and I need your help with a basic C console program.

if the user enters a ten-digit number and the fifth number is one, the output should be this word - "zadochno".

if the user enters a ten-digit number and the fifth number is two, the output should be this word - "redovno".

The user is expected to enter 2101162235 or similar. In any case, the fifth element should be either 1 or 2.

Examples:

Option 1: input> 2101162235 -> output string "zadochno"

Option 2: input> 2101262235 -> output string "redovno"

I am able to only partially create the program:

#include<iostream>

int number;
cout << "Please, enter number: ";
cin > number;

//I believe there should be an if statement or for loop here:
if(){

}

Can you please help me?

CodePudding user response：

You can take the input from the user as std::string and then check if the element at index 4 is 1 or 2 as shown below:

#include <iostream>
#include <string>
int main()
{
    std::string input;
    
    //take input from user 
    std::getline(std::cin, input);
    
    //check if the 5th letter(at index 4 since indexing starts with 0) is '1' or '2'
    if(input.at(4) == '1')
    {
        std::cout<< "zadochno"<<std::endl;
    }
    else if(input.at(4) == '2')
    {
        std::cout << "redovno"<<std::endl;
    }
    
    //this below shown for loop is optional. If you're sure that the user input contains only digits then you can skip/remove this for loop.
    for(int i = 0; i < input.size();   i)
    {
        //check if the all the characters are digits of a number 
        if(std::isdigit(input[i]))
        {
            ;//std::cout<<"yes digit";
        }
        else
        {
            std::cout<<"Please enter a valid number"<<std::endl;
        }
    }
    
    return 0;
}

The output of the above program can be seen here.

CodePudding user response：

Assuming the user does enter a 10 digit number (ie you don't need to check if they enter eg "foo" or "bar3000"), you can do the following:

Read the input as a std::string, not as int. User input is a string of characters always. Only if you need it you can get it converted to an integer. You do not need it as int. The n-th character of a std::string called user_input is user_input[n]. You just need to check whether the character in the middle is either '1' or '2'.

If you do need to check that the user did enter digits, you could use std::isdigit.

CodePudding user response：

I can offer the solution of your problem, using the algorithm Depth first search.

#include <iostream>
#include <string>
#include <vector>
using namespace std;
const int maximumSize=10;
vector<int> visited(maximumSize, 0);
void dfs(int current, int previous, int index, string input)
{
    if(visited[current]==1)
    {
        return;
    }
    if(input.size()!=10)
    {
        return;
    }
    if(current==(index-1))
    {
        if(input[current]=='1')
        {
            cout<<"zadochno"<<endl;
        }
        else
        {
            cout<<"redovno"<<endl;
        }
        return;
    }
    visited[current]=1;
    for(int next=(current 1); next<input.size();   next)
    {
        if(next==previous)
        {
            continue;
        }
        dfs(next, current, index, input);
    }
    return;
}
void solve()
{
    int number;
    cin>>number;
    string numberString=to_string(number);
    dfs(0, -1, 5, numberString);
    return;
}
int main()
{
    solve();
    return 0;
}

Input:

2101162235

Output:

zadochno

Input:

2101262235

Output:

redovno