Index of vector of strings in c++ [closed] - c++

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I have a vector of string including :- chemistry physics maths.
I want to access first character of each word ie c of chemistry p of physics and m of maths. How to do that?

Answer 1

You can output the first index element through this process.
I have made a 2D vector and applied a for loop so each row of the vector's first element is printed.
#include <iostream>
#include <vector>
int main()
{
std::vector<std::string> vec = {"chemistry", "maths", "physics"};
for(int i=0;i<vec.size();i++)
{
std::cout << vec[i][0];
}
return EXIT_SUCCESS;
}
You can also use a range based for loop
for (auto &i : vec)
std::cout << i[0] << " ";
The output will be
c m p

Answer 2

You can treat it like a 2D matrix of characters.
Given the vector of strings:
std::vector<std::string> vec = {"chemestry", "physics", "math"};
You can use a normal loop to access all first characters:
for (int i = 0; i < vec.size(); i++)
std::cout << vec[i][0] << " ";
Or a range based loop:
for (auto &str : vec)
std::cout << str[0] << " ";
Output:
c p m

Answer 3

I think this code should do the trick. If not then the Compiler is being a racist and doesn't like you that much. In that case you can just go-to your old buddy cpp.sh :D
String is a char Array and you can access it's contents from indexes like so
std::string str = "Hello";
std::cout << "First Index: " << str[0];
Output:-
H
Same goes for the vector as well
std::vector <char> str = "World!";
std::cout << "First Index: " << str[0];
Output:-
W
Now if you combine those two, it makes it a 2D Array so you have to access it like you access data from a 2D Array/Matrix.
std::vector <std::string> str = {"Hello", "World", "!"};
std::cout << "First Index Of Element 1: " << str[0][0] << std::endl
<< "First Index Of Element 2: " << str[1][0] << std::endl
<< "First Index Of Element 3: " << str[2][0] << std::endl;
Output:-
H
W
!
Program:-
#include <iostream>
#include <vector>
int main() {
std::vector <std::string> vec = {"chemistry", "physics", "math"};
for (int i=0; i < vec.size(); i++) { //-- size(); Function gives the size of a vector
std::cout << vec[i][0] << std::endl;
}
return 0;
}
Output:-
c
p
m
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