string iterator not stopping at end of string - c++

Question

I'm reading yummy recipes from a line made of different substrings divided by ; in this order:
Recipe index (R1)
Number to be cooked (1)
Recipe name (Ensalada Mixta)
Ingredients and their quantity (Lechuga 200;...)
The first three work like a charm, you can see they are stored in the data array and printed in the printf block. The problem comes reading the rest. The reader iterator reads through the line perfectly but doesn't stop at the end, so it add rubbish values to the pair and throws a segfault. Here's the output from this MRE:
:: R1
:: 1
:: Ensalada Mixta
-> Lechuga 200
-> Tomate 50
-> Pepino 50
-> Cebolla 50
-> Aceite Oliva 5
-> Vinagre De Vino 10
-> Sal 1
[1] 85313 segmentation fault (core dumped)
The loop should stop after Sal 1, so what am I doing terribly wrong? Here's the code:
#include <cmath>
#include <list>
#include <string>
#include <utility>
#include <cstdio>
using namespace std;
int main () {
string line = "R1;1;Ensalada Mixta;Lechuga 200;Tomate 50;Pepino 50;Cebolla 50;Aceite Oliva 5;Vinagre De Vino 10;Sal 1";
list<pair<string, unsigned> > ings;
string recipe_data[3];
string::const_iterator reader = line.cbegin();
//Lectura del código, plato y ing_name de la receta
for (int i = 0; i < 3; ++reader) {
if (*reader != ';')
recipe_data[i].push_back(*reader);
else
++i;
}
printf(":: %s\n", recipe_data[0].c_str());
printf(":: %s\n", recipe_data[1].c_str());
printf(":: %s\n", recipe_data[2].c_str());
/*
* This is the problematic loop. The problem is in the while boolean
* expression, which always evaluates to false.
*/
while (reader != line.cend()) {
string ing_name = "";
unsigned ing_quantity = 0;
while (*reader != ';' && reader != line.cend()) {
ing_name += *reader;
++reader;
}
string::reverse_iterator it = ing_name.rbegin();
for (int i = 0; *it != ' '; i++) {
char c[1] = {*it};
ing_quantity += atoi(c) * pow(10, i);
++it;
ing_name.pop_back();
}
ing_name.pop_back();
pair<string, unsigned> ing(ing_name, ing_quantity);
ings.push_back(ing);
printf("-> %s %d\n", ing.first.c_str(), ing.second);
++reader;
}
}
Here's gdb output using a breakpoint on the very last ++reader line:
Breakpoint 1, main () at so.cpp:52
52 ++reader;
1: reader = 59 ';'
2: line.cend() = 0 '\000'
3: ing = {first = "Tomate", second = 50}
(gdb)
Continuing.
-> Pepino 50
Breakpoint 1, main () at so.cpp:52
52 ++reader;
1: reader = 59 ';'
2: line.cend() = 0 '\000'
3: ing = {first = "Pepino", second = 50}
(gdb)
Continuing.
-> Cebolla 50
Breakpoint 1, main () at so.cpp:52
52 ++reader;
1: reader = 59 ';'
2: line.cend() = 0 '\000'
3: ing = {first = "Cebolla", second = 50}
(gdb)
Continuing.
-> Aceite Oliva 5
Breakpoint 1, main () at so.cpp:52
52 ++reader;
1: reader = 59 ';'
2: line.cend() = 0 '\000'
3: ing = {first = "Aceite Oliva", second = 5}
(gdb)
Continuing.
-> Vinagre De Vino 10
Breakpoint 1, main () at so.cpp:52
52 ++reader;
1: reader = 59 ';'
2: line.cend() = 0 '\000'
3: ing = {first = "Vinagre De Vino", second = 10}
(gdb)
Continuing.
-> Sal 1
Breakpoint 1, main () at so.cpp:52
52 ++reader;
1: reader = 0 '\000'
2: line.cend() = 0 '\000'
3: ing = {first = "Sal", second = 1}
(gdb) n
47 pair<string, unsigned> ing(ing_name, ing_quantity);
1: reader = 0 '\000'
2: line.cend() = 0 '\000'
3: ing = {first = "Sal", second = 1}
(gdb)
29 string ing_name = "";
1: reader = 0 '\000'
2: line.cend() = 0 '\000'
3: ing = {first = "Sal", second = 1}
(gdb)
28 while (reader != line.cend()) {
1: reader = 0 '\000'
2: line.cend() = 0 '\000'
(gdb)
29 string ing_name = "";
1: reader = 0 '\000'
2: line.cend() = 0 '\000'
3: ing = {first = "Sal", second = 1}
As you can see, it shouldn't have re-entered the loop since the iterator and cend() are equal, right?

Answer 1

The inner while increments until either you find ; or cend and in both cases you continue. Only on the next iteration you stop because reader != line.cend() is false but thats already too late.
Also you have to first check if you are at the end, and only then dereference reader:
while (reader != line.cend() && *reader != ';') {
ing_name += *reader;
++reader;
}
if (reader == line.cend()) break;