string concatenation

Question

I have a nested for loop and I need to convert the output I get to a string. How do I do that?

e.g. my loop gives hundreds of values of numbers like:

192 168 11 248
192 168 11 249
192 168 11 250
192 168 11 251
192 168 11 252
192 168 11 253
192 168 11 254
192 168 11 255

How do I concatenate each value as 192.168.11.248 and so on.

Basically every value needs to be converted from integer to string.

Answer 1

You need to look into the itoa and strncat methods.

Answer 2

As this is homework, I won't post complete code, just some tips: the functions you're looking for is snprintf, the safe version of sprintf. It has the advantage that you can also do the concatenation and the dots with it.

Alternatively, you could combine itoa and strncat, but itoa is no standard function.

Answer 3

If they are integers being generated you can utilize itoa and simply append that result to a character array of sufficient size with strcat.

Notice: itoa is non-standard, but it is also wide-spread and commonly used, and supplied as a non-standard library extension by many vendors. Keep in mind this means minor variations on non-standard behavior can cause significant issues in real world applications. If, however you are writing a homework assignment for one platform you will likely not encounter such issues. It is important to be aware of this and know that it won't stand up in the real world (not providing this warning was a defect in the original answer).

Other methods exist, snprintf being the chief one (with the advantage of standard behavior), but for the purpose of a simple exercise I opted to direct you to the simplest methods.

There are potential issues with some of the wide spread implementations of itoa which can crop up in edge cases, but the chance of that occurring with 3 digit positive integers is... Slim.

Regardless, go read up on snprintf as it is probably more useful in your studies of C, or if your environment supports it, consider investigating C++ and Boost as my first comment indicates a less error-prone solution in that language. C++ has the benefit of allowing for a type-safe method of specializing casts where snprintf can be easily misused (as can anything using ... and relying on a format string).

Answer 4

If you just need the output, you can do it without concatenation. Print every integer and a dot (.), except for the last integer. Pseudo code:

Print 192 "."
    Print 168 "."
        Print 11 "."
            Print 249 "\n"