Memory Leak Problem!

Code:

---

char* get(char buffer[],int from, int until, int len)
{
int a = from;
int b = 0;
int end = from+until;
char *lol;
lol = new char[until+1];
while (a < len && a <= end) {
lol[b] = buffer[a];
a++;
b++;
}
lol[b] = '\0';
return lol;
}

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That, as you can see, is causing a memory leak since i am using new.
The problem is i have no idea where to use delete.

After the return of the function.

Code:

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char *myChar = get (... parameters);

... do something with myChar.

delete[] myChar;

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oh i see, thanks! :)

Another problem:

What happens if you do

Code:

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printf(get(...para's))

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Quote:

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Originally Posted by HouseMD93

Another problem:

What happens if you do

Code:

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printf(get(...para's))

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A memory leak, and one you cannot fix making calls like that.

Why not drop using the memory allocation altogether, and return a std::string or even a container (i.e. vector<char>)?

Regards,

Paul McKenzie

Will it be ok if I use char instead of the pointer: char*?

Will that also cause a memory leak?

If you only want to return a single character, that'll work.

If you're interested in returning an entire string, then you have three basic options:
1) Allocate in the function and make sure you clean up after yourself.
2) Return a class type which automates cleanup internally. The most obvious such is std::string.
3) Make the output string a parameter so that no allocation is necessary. The downside here is that the caller needs to know how big to make the array.

Example:

Code:

---

#include <string>
std::string get(char buffer[],int from, int until, int len)
{
    int end = from + until;
    int maxChars = min(len, end);
    return std::string(buffer + from, maxChars);
}

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Not tested, but this should do the same thing as the code you have now, except that you are actually returning a string.

Regards,

Paul McKenzie

Ok thanks, although i have to rewrite every piece of code i have written. Atleast this way i won't get a memory leak.

It's probably better in the long run to rewrite using std::strings anyway.