void RemoveSpace(char *String)

{ int i=0,y=0; int leading=0;

for(i=0,y=0;String[i]!='\0';i++,y++)
{
    String[y]=String[i];    // let us copy the current character.

    if(isspace(String[i]))  // Is the current character a space?
    {
        if(isspace(String[i+1])||String[i+1]=='\0'||leading!=1) // leading space
            y--;
    }
    else
        leading=1;
}
String[y]='\0';

} Does this do the trick of removing leading and trailing whitespaces and replacing multiple whitespaces with single ones ?? i tested it for null string, all whitespaces, leading whitespaces and trailing whitespaces.

Do you think this is an efficient one pass solution ??