I want to convert from char to integer, following is the code-
FILE *p; char temp; int temp_int; p=fopen("week3data","r"); temp=getc(p); temp_int=atoi(temp) number in file goes from 1 to 200, need some guidance.
- 2Convert a single digit character, or convert a string containing a full three-digit number?Some programmer dude– Some programmer dude2015-08-18 08:57:52 +00:00Commented Aug 18, 2015 at 8:57
- 1What is the question exactly? Also pretty sure this is a duplicate...akalikin– akalikin2015-08-18 08:59:00 +00:00Commented Aug 18, 2015 at 8:59
- 3And are you sure you're programing in C++ and not C? There's no explicit C++ functionality in the code you show, only old C.Some programmer dude– Some programmer dude2015-08-18 08:59:03 +00:00Commented Aug 18, 2015 at 8:59
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2 Answers
If you're using C++, please use C++ SL:
std::fstream stream("file.txt", std::ios_base::in); float number; stream >> number; std::cout << number; Edit: Don't forget to check if your stream is valid:
if (!stream) { throw std::runtime_error("Cannot open file"); } 
Comments
If you're reading from a file, you shouldnt be using
temp=getc(p); and if you use
temp=fgetc(p); and the number is, for example 200, you will only read the "2".
so the answer is:
better use
char * buffer; fgets(buffer,10, p); temp_int=atoi(buffer); 6 Comments
akalikin
bufffer, not temp. Also what if the number is 10000000001? :)
Quentin
That
buffer looks a bit too uninitialized to be honest.akalikin
Actually buffer size 10 will do... Sorry
Dante's Dream
@Akalikin thanks for showing the mistake, it was buffer not temp. He said the numer goes between 1 and 200... so obviously with buffer size 10 its far enough... but what if number is 1000000000000? well this would be out of his problem.
Dante's Dream
@Quentin : im not giving him the whole code of course, i just gave him what he needed to reach the answer.
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