Fork() defining variable

Question

I am trying to implement the code below, but it gives me errors here:

char **lines = tokenizer(buffer, "\n"); //use of undeclared identifier 'lines'
free(lines); //use of undeclared identifier 'lines'

Actual code piece:

int child = fork();
switch (child) {
    case 0 :
        // child process
        char **lines = tokenizer(buffer, "\n");
        free(lines);

How can I resolve this?

Answer 1

A declaration is not permitted immediately after a case statement. There are three possble fixes:

• Enclose the code after the case in braces: case 0: { char **line = ...}.

• Move the declaration to just after the switch:

   switch (child) {
       char **lines;
       case 0:
           lines = tokenizer(buffer, "\n");
  

• Or, surprisingly, just add an extra ; after the case statement:

   switch (child) {
       case 0:
           ;
           char **lines = tokenizer(buffer, "\n");
  

See Why can't variables be declared in a switch statement?.

Answer 2

Looks like you are compiling it with a C compiler but use C++ syntax.

Try this:

{
    char **lines = tokenizer(buffer, "\n");
    free(lines);
}

As a note - if you try to share variable and populate it from a child process - this will not work.