[URI ONLINE JUDGE] – 1958 – Scientific Notation


Floating point numbers can be very long to show. In these cases, it is convenient to use the scientific notation.

You must write a program that, given a floating point number, shows this number in scientific notation: always show the mantissa sign; always show the mantissa with 4 decimal places; use the character ‘E’ between the mantissa and the exponent; always show the exponent sign; and show the exponent with at least 2 digits.


The input is a double precision floating point number X (according to the IEEE 754-2008 standard). There will never be a number with more than 110 characters long and more than 6 decimal places.


The output is the number X in a single line using the scientific notation detailed above. See the examples below.

Input Samples Output Samples
3.141592 +3.1416E+00
1.618033 +1.6180E+00
602214085774747474747474 +6.0221E+23
-0.000027 -2.7000E-05
-10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 -1.0000E+100

My solution:


#include <stdio.h>
#include <sstream>
#define SSTR( x ) dynamic_cast< std::ostringstream & >( \
( std::ostringstream() << std::dec << x ) ).str()

int main(int argc, char *argv[])
long double n;

scanf("%LE", &n);

std::string s = SSTR(n);

if(s[0] != '-')
printf("%.4LE\n", n);

return 0;




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