存储字符串数组以及通过每个字符串进行解析的问题C ++

Question

Okay so Basically my program begins by taking a users input. The input begins with an integer n specifying the number of commands to follow. After that line there will be n lines with a command on each line. I am trying to store each of these commands as a string in a string array, and then I am trying to process each string to find out what type of command it is and what numbers the user inputs on that same line.

Example Input:

./a

2

I 1 2

I 2 3

I want my program to then store each line, under the first input(2), into a string array. I then try to process each letter, and number in that single line.

My current code below:

#include <iostream>
#include <string>
using namespace std;

int main() {
int number_of_insertions;
cin >> number_of_insertions;
cin.ignore();

string commandlist[number_of_insertions];

for(int i = 0; i < number_of_insertions; i++) {
    string command;
    getline(cin, command);
    commandlist[i] = command;
}


string command;
char operation;
int element;
int index;
for(int i = 0; i < number_of_insertions; i++) {
    command = commandlist[i].c_str();
    operation = command[0];

    switch(operation) {
        case 'I':
            element = (int) command[1];
            index = (int) command[2];
            cout << "Ran insertion. Element = " << element << ", and Index = " << index << endl;
            break;
        case 'D':
            index = command[1];
            cout << "Ran Delete. Index = " << index << endl;
            break;
        case 'S':
            cout << "Ran Print. No variables" << endl;
            break;
        case 'P':
            index = command[1];
            cout << "Ran print certain element. Index = " << index << endl;
            break;
        case 'J':
        default:
            cout << "Invalid command" << endl;

    }
 }  
}

And then my output for the example input is as follows:

Ran insertion. Element = 32, and Index = 49

Ran insertion. Element = 32, and Index = 50

Not sure at all how to fix this problem, and looking forward to receiving some help from everybody.

Answer 1

The lines

        element = (int) command[1];
        index = (int) command[2];

don't convert the second and third tokens of command to an integer. They just take the integer values of the second and third characters of command and assign them to element and index , respectively.

What you need to do is extract tokens from command using some sort of parsing mechanism.

std::istringstream str(command);
char c;
str >> c; // That would be 'I'.

str >> element;
str >> index;

etc.