Remove whitespace from a string in-place, in linear time

void removeWhitespace(char\* str) {  
    int current \= 0;  
    int ahead \= 0;  
   
    while (str\[ahead\] !\= '\\0') {  
        while (str\[ahead\] \=\= ' ') ahead++;  
   
        str\[current\] \= str\[ahead\];  
        current++;  
        ahead++;  
    }  
}