Remove characters from a string in C

Question

I only have access to 'C' and need to replace characters within a character array. I have not come up with any clean solutions for this relatively simple procedure.

I am passed a character array, for example:

char strBuffer[] = "/html/scorm12/course/course_index.jsp?user_id=100000232&course_id=100000879&course_prefix=ACQ&version=2&scorm_version=3&roster_id=100011365&course_name=Test%20Course%201.2&mode=browse&course_number=0000&mode_id=1";

I need to modify this buffer to replace all the & with &. The resulting buffer does not have to overwrite strBuffer (a new buffer can be created).

Any suggestions?

Edit:

In the past I have done the strstr function in a loop, but was looking for a simpler solution, perhaps the C equivalent to the String.Replace method.

Edit:

For my immediate needs, the following is all that I need.

char strBuffer[] = "/html/scorm12/course/course_index.jsp?user_id=100000232&course_id=100000879&course_prefix=ACQ&version=2&scorm_version=3&roster_id=100011365&course_name=Test%20Course%201.2&mode=browse&course_number=0000&mode_id=1";
char strTemp[1024];
char *s = (char*)strBuffer;
int i=0;

while (*s)
{
    strTemp[i++] = *s;
    if (strncmp(s,"&",5) == 0)
    {
        s += 5;
    }
    else
        s++;
}
strTemp[i] = 0;

Future modifications:

• Create a utility function to store this function.
• Pass the search string as a parameter.
• Determine the search string's length, so the hardcoded 5's can be removed.
• Dynamically allocate the strTemp variable.
• Error checking for empty strings and chars not found.

EDIT:

I created a blog post to detail the steps and provide a more flexible solution:

http://www.solutionmaniacs.com/blog/2012/11/25/c-removereplace-characters-in-a-string.html

Answer 1

char *s = (char*)strBuffer;
char sClean[strlen(strBuffer) + 1]; /* +1 for null-byte */
/* if above does not work in your compiler, use:
    char *sClean = (char*)malloc(sizeof(strBuffer) + 1);
*/
int i=0;
while (*s)
{
    sClean[i++]= *s;
    if ((*s == '&') && (!strncmp(s, "&", 5)) s += 5;
    else s++;
}
sClean[i] = 0;

Answer 2

Basically, you need to:

• use the strstr() function to find the "&"s
• copy characters to the resulting buffer up to the position found
• skip 4 characters
• repeat until NUL

Answer 3

Allocate another buffer, either on the stack or the heap, and then copy the string into the new buffer 1 character at a time. Make special handling when you encounter the & character.

Answer 4

C isn't noted for it's ease of use, especially when it comes to strings, but it has some rather nice standard library functions that will get the job done. If you need to work extensively on strings you'll probably need to know about pointers and pointer arithmetic, but otherwise here are some library functions that will undoubtedly help you:

• strchr() to find a character (say, '&') in a string.
• strcmp() and strncmp() to compare two strings.
• strstr() to find a substring in a string (probably easier and faster than using the strchr()/strcmp() combination).
• malloc() to allocate a new string.