如何在字符串中从头到尾移动char

Question

As the title says, in my program I (after many procedures) get tokenized words. Unfortunately due to reversing them they hold punctuation characters at the beginning of a word eg. ,moose

How to move that , from the beginning to the end -> moose,

Up to now I've tried( ptr is char * ):

temp = strdup(ptr);
temp = &ptr[0];
ptr[0] = ptr[1];
ptr[strlen(ptr)-1] = temp;
free(temp);

But that gives me errors:

assignment makes pointer from integer without a cast

warning: assignment makes integer from pointer without a cast

How to fix that?

Answer 1

Something like this:

void swap_last(char *str)
{
  const size_t len = strlen(str);
  if(len > 1)
  {
    const char   first = str[0];
    memmove(str, str + 1, len - 1);
    str[len - 1] = first;
  }
}

Note that the above assumes str to be valid.

Answer 2

Generally, the comma should be its own token, so parsing it post-tokenizing is putting a second tokenizer after the first.

The best solution is to not just split on white space, but to recognize the comma as it's own token, so you can then test the presence of comma's as part of the grammar.

Answer 3

Reviewing your code and extrapolating for its lack of types, it's difficult to know the type of your temp variable -- because in some places you're using it like a char * and in others you're using it like a char .

I suspect the compiler error is on line ptr[strlen(ptr)-1] = temp; (because I suspect that temp is a char * ), and the proper fix is: ptr[strlen(ptr)-1] = *temp;