C++ read number string and capture specific position character as int - c++

Question

I need my program to read a string of numbers input by the user and then assign each number to an int variable:
94715 is input by the user as string
then
a=9
b=4
c=7
d=1
e=5
so I can
if (a < b), c*d+e, a-e, etc
I've searched some commands (getline, string.substr(ind,n), getc, fgetc, atoi, etc) I know I'm close but I can't find examples of exactly what I'm looking for.
The simplest and most direct way I've found is
stringstream convert(string1);
convert>>variable;
but it converts the whole string, if there was a way to add an ind position in it like
string1.substr(0,1)
that'd do the trick...

Answer 1

It is as simple as this:
std::string num = "94715";
size_t i = 0;
assert( num.length() > 4 );
int a = num[i++] - '0';
int b = num[i++] - '0';
int c = num[i++] - '0';
int d = num[i++] - '0';
int e = num[i++] - '0';
note: this may not work properly on systems not using ACII encoding, but it is unlikely you would hit such problem.

Answer 2

int number = 9544;
int vector[10]; // you can make it as big as you want or simply use std::vector
int position = 0;
while (number != 0)
{
vector[position++] = number % 10; // this assigns the last digit
number = number / 10; // remove the last digit
}
for(int i=0; i<position; i++)
std::cout << vector[i]; // this will print 4459
Now you have your number's digits inside an int vector.

Answer 3

This example uses chars because a string is still a char array.
This is for if you are on Windows. Just input and press the enter key.
Like Dieter Lücking suggested, it does this character by character.
It uses kbhit() and getch() found in conio.h to process single characters.
Then it multiplys the characters with appropiate position to get full integer.
And then it stores them in the array digitArray[ ], and assigns them to a,b,c,d or e after. Now you can do whatever with a,b,c,d and e.
Here is some code to demonstrate.
// Re: Now it is just clunky
// one ten hundred thousand
// 1 2 3 4
//digitn=digitArray[3]*1 + digitArray[2]*10 +digitArray[1]*100 +digitArray[0]*1000
#include <iostream>
#include <conio.h>
#include <stdio.h>
#include <stdlib.h>
#include <string>
using namespace std;
int digit=0,digitInput=0;
int digitArray[10]={0},digitn;
int numberOfInputDigits=7;
void SplitIntoDigits(void);
int a=0,b=0,c=0,d=0,e=0,f=0;
int main(){
system("color 1F"); //Blue background
while(1){
cout<<"\nPlease enter number. Max Input is "<<numberOfInputDigits<<" individual digits \n";
cout<<"or press enter when done \n>" ;
memset(digitArray,0,sizeof(digitArray));
a=0;b=0;c=0;d=0;e=0;f=0;
SplitIntoDigits();
//cout<<"\n"<<digitArray[7]="<<digitArray[7];
cout<<"\n\n";
a = digitArray[0];
b = digitArray[1];
c = digitArray[2];
d = digitArray[3];
e = digitArray[4];
f = digitArray[5];
cout<<"a = "<< a <<"\n";
cout<<"b = "<< b <<"\n";
cout<<"c = "<< c <<"\n";
cout<<"d = "<< d <<"\n";
cout<<"e = "<< e <<"\n";
cout<<"f = "<< f <<"\n";
cout<<"\n\n The whole combined int number is "<<digitn<<"\n\n";
}
return 0;
}
/*********************************
* *
********************************/
void SplitIntoDigits(void){
digitArray[0]=0;
digitArray[1]=0;
digit=0;
digitInput=0;
while((digit<numberOfInputDigits)){
if (kbhit()){
digitInput=getch();
if (digitInput==27) exit(0);
if ((digitInput>47) && (digitInput<59)) {
digitArray[digit]=(unsigned char)digitInput-48;
digit++;
cout<<digitInput-48;
}
if (digitInput==13) { digitn=digitArray[0]; break; }
}
}
switch(digit) {
case 0:
case 1:
digitn=digitArray[0]*1 ;
break;
case 2:
digitn= digitArray[1]*1 +digitArray[0]*10 ;
break;
case 3:
digitn= digitArray[2]*1+digitArray[1]*10 +digitArray[0]*100 ;
break;
case 4:
digitn=digitArray[3]*1+digitArray[2]*10+digitArray[1]*100+digitArray[0]*1000 ;
break;
case 5:
digitn=digitArray[4]*1+digitArray[3]*10+digitArray[2]*100+digitArray[1]*1000+digitArray[0]*10000 ;
break;
case 6:
digitn=digitArray[5]*1+digitArray[4]*10+digitArray[3]*100+digitArray[2]*1000+digitArray[1]*10000
+digitArray[0]*100000;
break;
case 7:
digitn=digitArray[6]*1+digitArray[5]*10+digitArray[4]*100+digitArray[3]*1000+digitArray[2]*10000
+digitArray[1]*100000 +digitArray[0]*1000000;
break;
case 8:
digitn=digitArray[7]*1+digitArray[6]*10+digitArray[5]*100+digitArray[4]*1000+digitArray[3]*10000
+digitArray[2]*100000 +digitArray[1]*1000000+digitArray[0]*10000000;
break;
case 9:
digitn=digitArray[8]*1+digitArray[7]*10+digitArray[6]*100+digitArray[5]*1000+digitArray[4]*10000
+digitArray[3]*100000 +digitArray[2]*1000000+digitArray[1]*10000000 +digitArray[0]*100000000;
break;
}
// if (digitInput!=13) digitn=digitArray[3]*1+digitArray[2]*10+digitArray[1]*100+digitArray[0]*1000 ;
//cout<<("\n%i\n\n",digitn);
}
/*********************************
* *
********************************/