Here is one way but the problem with it is unnecessary usage of output screen.
lenth=printf("%d",num);// or lenth=printf("%s",str);
How could i find length without having output from printf?
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Use `strlen` function for string. – haccks Jul 14 '15 at 17:20
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1Do you mean, to find a length of decimal number representation? – Eugene Sh. Jul 14 '15 at 17:20
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8C or C++? Pick one... – Lightness Races in Orbit Jul 14 '15 at 17:20
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2For a number or a string? Because they aren't the same internally ... – AntonH Jul 14 '15 at 17:22
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i want to reduce my execution time for online submission so dosent matter but basically C – wrangler Jul 14 '15 at 17:23
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@AntonH more for a number – wrangler Jul 14 '15 at 17:24
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@Abhishek Use modulus and count the digits for a number (+1 for sign). – πάντα ῥεῖ Jul 14 '15 at 17:25
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You probably just want to divide by 10 repeatedly until you get zero, not counting an initial zero. If you really must go the printf route, there's sprintf to print to a buffer - but don't do that. – Rup Jul 14 '15 at 17:26
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Use a raw literal operator template and return sizeof...(cs) where cs is a char parameter pack. – David G Jul 14 '15 at 17:26
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@πάνταῥεῖ it takes more time as the size of a number increases....and less efficient than that given above..... – wrangler Jul 14 '15 at 17:28
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@0x499602D2 please elaborate – wrangler Jul 14 '15 at 17:28
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2@Abhishek Then use something like `std::to_string(num).size();` – πάντα ῥεῖ Jul 14 '15 at 17:29
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2just use `snprintf` with big enough buffer – Slava Jul 14 '15 at 17:29
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3Oh come on, it's perfectly clear what he's asking. – QuestionC Jul 14 '15 at 17:30
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See http://stackoverflow.com/questions/7384956/is-there-a-file-pointer-file-that-points-to-nothing – QuestionC Jul 14 '15 at 17:30
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1@QuestionC not really – Slava Jul 14 '15 at 17:30
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`strlen("string")` works for a string in C. In C++ you can use `std::string str = "hello";`. In terms of int, I'll direct you here: http://stackoverflow.com/q/9655202/2986033 – Colin Jul 14 '15 at 17:31
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2@πάνταῥεῖ `std::to_string(num).size();` should be an answer. It's informative and will serve to educate those coming after who may have the same question. – Richard Hodges Jul 14 '15 at 17:33
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@RichardHodges Unfortunately the OP seems quite resistant to decide for [tag:c] or [tag:c++], also the question's [on hold] for now. No question improvement, no answer. – πάντα ῥεῖ Jul 14 '15 at 17:34
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_@Abhishek_ As you have decided for [tag:c] finally you should use something like @Slava suggested along with `stren()`. – πάντα ῥεῖ Jul 14 '15 at 17:43
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@Abhishek Look here: https://stackoverflow.com/questions/3068397/finding-the-length-of-an-integer-in-c or here: https://stackoverflow.com/questions/4143000/find-the-string-length-of-an-int – AntonH Jul 14 '15 at 17:45
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1@QuestionC It takes a certain amount and sort of intelligence to look at the question and infer what is (obviously) being asked. Empirical evidence suggests that most people lack it. – Jim Balter Jul 14 '15 at 19:21
1 Answers
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You can use snprintf() with an empty buffer (i.e. pass a null pointer), which will return the number of characters that would have been written into the buffer if there was enough space in it:
int length = snprintf(0, 0, "%d", num);
This way, you don't need to use an actual buffer and it won't print on stdout like printf() does.
