What does “%.*s” mean as a format specifier in printf?

Question

Can anyone tell me what this means: "%.*s"

For example, it is in use here:

  sprintf(outv->deliveryAddressCity, 
          "%.*s",
          sizeof(outv->deliveryAddressCity)-1,
          mi->deliveryAddressCity);

Answer 1

%.*s means print the first X number of characters from the following buffer . In this case, print the first sizeof(outv->deliveryAddressCity) - 1 characters from mi->deliveryAddressCity , preventing writing beyond the bounds of outv->deliveryAddressCity .

A shorter example:

printf("%.*s", 4, "hello world");

would print hell .

Answer 2

Maybe you can get it with this example:

printf("%.*s", 3, "abcdef");

prints "abc".

Answer 3

.* The precision is not specified in the format string, but as an additional integer value argument preceding the argument that has to be formatted.

So in your case the size of the string is sizeof(outv->deliveryAddressCity )-1

Answer 4

The width and precision formatting parameters may be omitted, or they can be a fixed number embedded in the format string, or passed as another function argument when indicated by an asterisk "*" in the format string. For example printf("%*d", 5, 10) will result in " 10" being printed, with a total width of 5 characters, and printf("%.*s", 3, "abcdef") will result in "abc" being printed.

(It was really easy to find it on a search engine...)

Answer 5

It is most commonly used when you have a string that is not null terminated, and the length is stored elsewhere.

For example:

{
    char* regular_string = "Hello World";  // This string has a null-Terminator.

    char untermed_string[11];
    int len;

    // Specifically make untermed string so it is NOT null-terminated.
    memcpy(untermed_string, regular_string, 11);
    len = 11;

    printf("The string is %.*s\n", len, untermed_string); // This will still print the proper data!
    printf("The start of the string is %.*s\n", 5, untermed_string); // This will only print "Hello".
}

Answer 6

this is a format-specifier, which takes 2 values from the stack, the first is the size, the second the value.

The .-notation: atleast-length.maxlength (so ".*" means: max * characters)

Answer 7

it helps you to print the part of the string . u can specify to what length u have to print the string . example : printf("%.*s", 5, ,"rahul subedi") output: rahul