Convert string into int and char

Question

How can I convert a string to int and char, with fixed number of positions, in C++? For example: I need to convert "A1920139" into char "A", int 192 (next three positions in the string), int 01 (following two positions), and int 39 (last two positions).

So far I have only managed to get each int by itself (1, 9, 2, 0, etc). I don't know how to get the char or define a fixed number of positions for the int. This is what I have managed to write:

string userstr;
int* myarray = new int[sizeof(userstr)];

userstr = "A1920139";

for (i = 1; i < userstr.size(); i++) {
   myarray[i] = userstr[i] - '0';
}

for (i = 1; i < userstr.size(); i++) {
   printf("Number %d: %d\n", i, myarray[i]);
}

Eventually I need to arrive at something like char="A", int_1=192, int_2=01, and int_3=39

int* myarray = new int[sizeof(userstr)]; - why manual memory management (new) rather than using a container or (at least) a smart pointer? — Jesper Juhl
– Jesper Juhl, Commented Aug 13, 2019 at 17:26
Duplicate of stackoverflow.com/questions/12119645/… I can't close because I already accidentally closed with the wrong link. This is regarding new int[sizeof(userstr)];. But since OP used .size() later, it may just be a typo. — François Andrieux
– François Andrieux, Commented Aug 13, 2019 at 17:26
On second though, it seems the question is more broad than that. OP is trying to group the string into batches of digits and may not have noticed the effects of undefined behavior yet. The duplicate only addresses a problem with the code but it's not what is being asked. — François Andrieux
– François Andrieux, Commented Aug 13, 2019 at 17:28
Another note: Even if you change to int* myarray = new int[userstr.size()];, userstr's size will be zero at that point. It hasn't been assigned anything yet. ` — user4581301
– user4581301, Commented Aug 13, 2019 at 17:29
how is my question duplicate of that in the link? I don't see an answer to my question in that link - it only relates to getting the size of a string? — Carlos Martins
– Carlos Martins, Commented Aug 13, 2019 at 17:34

rustyx · Accepted Answer · 2019-08-13 17:35:53Z

2

If I understand correctly, you want to parse a string at fixed positions, in that case you can use substr() and stoi() like this:

std::string userstr = "A1920139";
int myarray[3];

myarray[0] = std::stoi(userstr.substr(1, 3));
myarray[1] = std::stoi(userstr.substr(4, 2));
myarray[2] = std::stoi(userstr.substr(6, 2));

std::cout << "int_1=" << myarray[0] << ", int_2=" << myarray[1] << ", int_3=" << myarray[2] << std::endl;

answered Aug 13, 2019 at 17:35

rustyx

86.4k28 gold badges224 silver badges298 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Wyck · Accepted Answer · 2019-08-13 17:39:29Z

1

substr(pos, len) will get a substring starting at position pos of length len.

stoi will convert a string to an integer.

#include <string>
#include <iostream>

int main()
{
    std::string userstr = "A1920139";

    char c = userstr[0];
    int n1 = std::stoi(userstr.substr(1, 3));
    int n2 = std::stoi(userstr.substr(4, 2));
    int n3 = std::stoi(userstr.substr(6, 2));

    std::cout << c << ' ' << n1 << ' ' << n2 << ' ' << n3 << std::endl;
}

answered Aug 13, 2019 at 17:39

Wyck

12.1k8 gold badges50 silver badges93 bronze badges

Collectives™ on Stack Overflow

Convert string into int and char

2 Answers 2

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related