updating part of string in c++

Question

Is there any way to update the part of a string by passing it in a function?

std::string str = "hello world";

I want to reverse part of the string for example from index 4 to 8.

I have a function that reverses a string from start index to end index. How I can pass the string from index 4 to 8 to that function so that it will be updated automatically in the str string.

What's the declaration of your "reverse function"? – Kiril Kirov Oct 18 '12 at 10:44 — Kiril Kirov, Oct 18 '12 at 10:44
post the code that you have... – gexicide Oct 18 '12 at 10:45 — gexicide, Oct 18 '12 at 10:45
Study carefully http://www.cplusplus.com/reference/string/ – Basile Starynkevitch Oct 18 '12 at 10:46 — Basile Starynkevitch, Oct 18 '12 at 10:46

score 4 · Answer 1 · edited Oct 19 '12 at 09:30

4

Why don't you just use std::reverse?

std::string str = "hello world";
std::reverse ( str.begin() + 4, str.begin() + 8 );

edited Oct 19 '12 at 09:30

answered Oct 18 '12 at 10:48

Benj

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score 2 · Answer 2 · answered Oct 18 '12 at 10:46

2

Write a function that takes begin/end iterators. See, for example std::reverse(). Usage example for std::vector is on the same page.

answered Oct 18 '12 at 10:46

bobah

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@Madu, you can actually use `std::reverse()` instead of writing new function. – Paul Oct 18 '12 at 10:48

score 1 · Answer 3 · answered Oct 18 '12 at 10:46

You can pass the string by reference:

void foo( std::string & inputString )
{
  //anything you do here will directly affect the string passed.
}

For example:

void foo( std::string & str )
{
    str.append("World!");
}

int main()
{
    std::string a = "Hello, ";
    foo(a);
    std::cout << a;
    return 0;
}

will print out "Hello, World!". Another choice is to pass the begin and end iterators of the string. A lot of std functions work like that.

updating part of string in c++

3 Answers3