C++: Global replacement of a character within a string

[ineedhelpnow]

Complete the function to replace any period by an exclamation point. Ex: "Hello. I'm Miley. Nice to meet you." becomes:

"Hello! I'm Miley! Nice to meet you!"
Sample program:

#include <iostream>
#include <string>
using namespace std;

void MakeSentenceExcited(string& sentenceText) {
<STUDENT CODE>
}

int main() {
string testStr;

testStr = "Hello. I'm Miley. Nice to meet you.";
MakeSentenceExcited(testStr);
cout << testStr;

return 0;
}i came up with
int pos = sentenceText.find('.');
while()
{
sentenceText.replace(pos, 1, "!");
pos = sentenceText.find('.', pos+1);
}
but i don't know what goes int he while loop. please help. its almost due...

 

[MarkFL]

What does the find method return if the character is not found? You could also do this with a call to the find method in the condition of the while loop only.

By the way, this would be a snap in javascript:

[m]str = str.replace(/\./g, "!");[/m] :D

 

[I like Serena]

By the way, this would also be a snap in javascript:

[m]str = str.replace(/\./g, "!");[/m] :D

If we use QString::replace from the Qt framework, this would be a snap in C++:

[m]str = str.replace(".", "!");[/m] ;)

Unfortunately the std::string from the Standard C++ Library offers a rather limited set of functions.

 

[johng1]

Hi,
Unless this is an exercise in using the member functions of class string, I think a simple traversal of the string is probably better. As an old CS teacher, I believe the idea of traversal (iteration) of a data structure is best learned by first learning to traverse an array. Here's simple code:

void MakeSentenceExcited(string& sentenceText) {
    for (int i=0;i<sentenceText.length();i++) {
        if (string[i]=='.') {
            string[i]='!';
        }
    }
}

Btw, the above code wouldn't work in Java since Java Strings are immutable (const in C++ parlance). Also a Java String s has a method replace which returns a new string. So as above, one can make a one line method call.

 

[LudusRex]

Hello! I'm Miley! Nice to meet you!

Great job on coming up with a solution for this problem! Your code is on the right track, but there are a couple of things that need to be fixed in order for it to work properly.

First, the while loop condition should be "pos != string::npos". This will ensure that the loop continues until all periods have been replaced.

Second, the "pos" variable should be updated within the loop to avoid an infinite loop. You can do this by setting "pos" equal to the result of "sentenceText.find('.', pos+1)".

Lastly, you can also add a check before the while loop to make sure that the string actually contains a period before attempting to replace it. This can be done by using an if statement with the condition "sentenceText.find('.') != string::npos".

With these changes, your code should look something like this:

int pos = sentenceText.find('.');
if (pos != string::npos) {
while (pos != string::npos) {
sentenceText.replace(pos, 1, "!");
pos = sentenceText.find('.', pos+1);
}
}

I hope this helps! Keep up the good work.