How to remove all spaces and tabs from a given string in C language?

Question

What C function, if any, removes all preceding spaces and tabs from a string?

Thanks.

Answer 1

In C a string is identified by a pointer, such as char *str, or possibly an array. Either way, we can declare our own pointer that will point to the start of the string:

char *c = str;

Then we can make our pointer move past any space-like characters:

while (isspace(*c))
    ++c;

That will move the pointer forwards until it is not pointing to a space, i.e. after any leading spaces or tabs. This leaves the original string unmodified - we've just changed the location our pointer c is pointing at.

You will need this include to get isspace:

#include <ctype.h>

Or if you are happy to define your own idea of what is a whitespace character, you can just write an expression:

while ((*c == ' ') || (*c == '\t'))
    ++c;

Answer 2

void trim(const char* src, char* buff, const unsigned int sizeBuff)
{
    if(sizeBuff < 1)
    return;

    const char* current = src;
    unsigned int i = 0;
    while(current != '\0' && i < sizeBuff-1)
    {
     if(*current != ' ' && *current != '\t')
      buff[i++] = *current; 
     ++current;
    }
    buff[i] = '\0';
}

You just need to give buff enough space.