c++ Expression: string subscript out of range error - c++

Question

hello i am new to programming but every time i run this code i get the error "c++ Expression: string subscript out of range" i am pretty sure that the error is in the second for loop
#include<iostream>
#include<string>
#include <algorithm>
using namespace std;
int main()
{
string x;
string n;
cin >> x;
for (int i = 0; i <= x.length(); i++){
if (x[i] == 'a' || x[i] == 'e' || x[i] == 'i' || x[i] == 'o' || x[i] == 'u' || x[i] == 'y')
{
x[i] = ' ';
}
}
x.erase(remove_if(x.begin(), x.end(), isspace), x.end());
int f = x.length() * 2;
for (int i = 0; i <f-1; i+=2){
n[i] = '.';
}
cout << n << endl;
}

Answer 1

for (int i = 0; i <= x.length(); i++)
should be:
for (int i = 0; i < x.length(); i++)
because index starts from 0

Answer 2

x[x.length()] out of range
can not use n[index] when the size of n is 0,use n.push_back()
for (int i = 0; i < x.length(); i++){ //error
if (x[i] == 'a' || x[i] == 'e' || x[i] == 'i' || x[i] == 'o' || x[i] == 'u' || x[i] == 'y')
{
x[i] = ' ';
}
}
x.erase(remove_if(x.begin(), x.end(), isspace), x.end());
int f = x.length() * 2;
for (int i = 0; i <f-1; i+=2){
n[i] = '.'; // n.push_back('.');
}
cout << n <
< endl;

Answer 3

If you are trying to remove all the vowels from your input string, you do not need to run two separate loops. You are already using std::remove_if, just add lambda shown in following code and you will have your desired output.
#include <iostream>
#include <algorithm>
#include <string>
#include <cctype>
using namespace std;
int main() {
std::string str = "This is test of vowels aeiou to be removed. Also the upper case AEIOU.";
std::cout << "Original String: " << str << std::endl;
str.erase(std::remove_if(str.begin(), str.end(), [](char x) {
return (x == 'a'|| x == 'e' || x == 'i' || x == 'o' || x == 'u' || x == 'y'
|| x == 'A'|| x == 'E' || x == 'I' || x == 'O' || x == 'U' || x == 'Y')
}), str.end());
std::cout << "String with vowels removed: " << str << std::endl;
// Not sure what you are trying to achieve with this code.
int f = x.length() * 2;
for (int i = 0; i <f-1; i+=2)
{
n[i] = '.';
}
return 0;
}
Here is the LiveDemo

Answer 4

You have 3 bits of code causing errors:
1) Your first error occurs because you should be checking that i < x.length() in the first loop condition, not that i <= x.length() . Even better, calculate the length once and then use that value in the loop condition to avoid calling x.length() repeatedly. Your first loop should look like this:
int length = x.length();
for (int i = 0; i < x.length(); ++i)
note: ++i is quicker than i++ and in this case using ++i would not make a difference to the logic.
2) Your second error is due to the line int f = x.length() * 2 because you are doubling the length of the array and then using that number to iterate through the array. For example, if your array has a length() of 5 then int f = x.length() * 2 would mean that f = 10 but if the length of the array is 5 than accessing the array with any number greater than 4 (array index starts at zero) would produce an error. In your second loop condition you do this
for (int i = 0; i < f-1; i+=2 ) {
n[i] = '.' // i could easily be more than 4 at this point
}
To fix you second problem, take out the * 2 from int f = x.length() * 2
3) Your third is because you haven't given the n string object a value yet you are accessing it using array indexing []