How to write floats to a C-string?

Question

I am new to working with arrays in C and I am trying to store a string like so:

//x, y, p are floats
("X: %f\nY: %f\nP: %f", x, y, p)

into an array.

I do not know how to read in the values x, y, p so that the array stores it as a single string.

Is it possible? If not, how should I do this?

UPDATE

So apparently people don't understand what I mean.

The above is not my specific code, it is the string I wish to store; an example.

printf("X: %f\nY: %f\nP: %f", x, y, p);

is equal to when printed in the command:

X: 10.000000
Y: 12.000000
P: 32.000000

This is how I wish to store it in an array, instead, it is recognising it as 4 arguments, instead of 1.

How can I make it recognise it as one argument?

[use sprintf?](http://www.cplusplus.com/reference/cstdio/sprintf/?kw=sprintf) just remember to make sure the output buffer is large enough — quetzalcoatl, Aug 10 '15 at 14:39
@Sourav Ghosh FWIW: `"X: %f\nY: %f\nP: %f"` is a string and an array. Yet in OP's case the destination string is likely implied. — chux - Reinstate Monica, Aug 10 '15 at 14:41
possible duplicate of [simple use of sprintf c](http://stackoverflow.com/questions/8232634/simple-use-of-sprintf-c) -- please use this link if confirming a duplicate. The previous one was very narrow and about a bug in some version of gcc — quetzalcoatl, Aug 10 '15 at 14:42
To form a right-sized buffer and print use `int n = snprintf(NULL, 0, "X: %f\nY: %f\nP: %f", x, y, p); char buf[n+1]; snprintf(buf, sizeof buf, "X: %f\nY: %f\nP: %f", x, y, p); ` — chux - Reinstate Monica, Aug 10 '15 at 14:45
@quetzalcoatl I have not heard of it, wouldn't have asked otherwise. Plus the question title, and content does not make reference, so while there may be a suitable answer, it's by no means a duplicate. — App Dev Guy, Aug 10 '15 at 14:51

score 1 · Accepted Answer · answered Aug 10 '15 at 14:46

1

You can use sprintf or snprintf. Here array is your C-string array (char *array[n]):

array[x] = malloc(64);
snprintf(array, 64, "X: %f\nY: %f\nP: %f", x, y, p);

snprintf is safer because you can set the maximum number of characters it should write.

I picked the magic number 64 here, but you should make sure to allocate enough memory to store the result string with the converted floats.

answered Aug 10 '15 at 14:46

Emil Laine

That is perfect. Thank you a million my friend. I am glad you understood what I was meaning, I copped a lot of hate on this question. – App Dev Guy Aug 10 '15 at 15:02

1 Answers1