String manipulation C++ - c++

Question

I need to make some functions but i don't know how.
join two strings, input positions and output the characters from the position in the string
Example: s1=first, s2=second; s1+s2=firstsecond, pos=3,7,10, output=ren
this is my code for one postion, but i don't know how to make for several position, main problem is how to limit input of position:
s=s1+s2;
cin>>pos;
cout<<s[pos-1];
define vowel in string and replace that vowel with string
Example: s=firstsecondthird, vowel=i, str=EXA, output=fEXArstsecondthEXArd
This is what i know, i don't know how to make the replacing vowel with string(str)
cin>>vowel;
if(check is defined character vowel)
{
cin>>str;
.
.
.
}
Thank you

Answer 1

Catch! :)
#include <iostream>
#include <string>
#include <cstring>
int main()
{
std::cout << "Enter first string: ";
std::string s1;
std::cin >> s1;
std::cout << "Enter second string: ";
std::string s2;
std::cin >> s2;
s1 += s2;
std::cout << "The joined string is " << s1 << std::endl;
std::cout << "Enter several positions in the joined string (0-stop): ";
std::string s3;
std::string::size_type pos;
while ( std::cin >> pos && pos != 0 )
{
if ( --pos < s1.size() ) s3 += s1[pos];
}
std::cout << "You have selected the following letters " << s3 << std::endl;
const char *vowels = "aeiou";
char c;
do
{
c = '\0';
std::cout << "Enter a vowel: ";
} while ( std::cin >> c && !std::strchr( vowels, c ) );
if ( c != '\0' )
{
for ( auto pos = s1.find( c, 0 );
pos != std::string::npos;
pos = s1.find( c, pos ) )
{
const char *t = "EXA";
const size_t n = 3;
s1.replace( pos, 1, t );
pos += n;
}
std::cout << "Now the joined string looks like " << s1 << std::endl;
}
return 0;
}
If to enter
first
second
3 7 10 0
i
then the program output will be
Enter first string: first
Enter second string: second
The joined string is firstsecond
Enter several positions in the joined string (0-stop): 3 7 10 0
You have selected the following letters ren
Enter a vowel: i
Now the joined string looks like fEXArstsecond
You can use it as a template for your great program.:)