Creating a string from a character array

[Milan]

Hi all,

I would like to use the strcmp - string compare function, however don't know how to create a string from character array. Standard way would be something like this:

char arr[ ] = "Hello World";
string str(arr);

However the compiler doesn't like the type string. Is there a way to create a string that I could use such as in the following example?

if(strcmp("Hello World",str) == 0)
{do something}

Regards

Milan

[Matt Barr]

Hi Milan, perhaps your C platform is buggy, or maybe there's something else going on in your test case, but strcmp should not tell you a string matches an initial sub-string.

Given a compliant strcmp implementation (as in John's example, or the standard C library), the code snippet:

char buf[BUFSZ];

strcpy (buf, "rat");
(void) printf ("%s %s rate\n", buf, (strcmp (buf, "rate")) ? "!=" : "==");
strcpy (buf, "rate");
(void) printf ("%s %s rate\n", buf, (strcmp (buf, "rate")) ? "!=" : "==");
strcpy (buf, "rated");
(void) printf ("%s %s rate\n", buf, (strcmp (buf, "rate")) ? "!=" : "==");

should produce:

rat != rate
rate == rate
rated != rate

The return 0 in the strcmp example John posted is hit only when *s1 == *s2 and *s1 == 0, so *s2 == 0 as well. The for loop exits on the first difference and returns non-zero, so regardless of operand order that code will return 0 only when the two strings are identical.

[John]

Are you making sure to clear the buffer pointed to by p_data after each comparison? If you are reusing the same buffer and not clearing it, that would explain your behavior as the "rate" string is already in the buffer.