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Write a C program to convert a number in scientific notation to its equivalent decimal form :
Given
8.3e+2 output = 830
2.E-1 output = 0.2
4.3E2 output = 430
Is there any inbuilt library or function in C/C++ which can do this?
or one will have to write his own code, in that case, any easy way to achieve this?
try this
#include <iostream>
#include <string>
int32_t main(int32_t argc, char *argv[]) {
std::string str = "8.3e+2";
std::cout << std::stod(str) << std::endl;
return EXIT_SUCCESS;
}
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Hi I was wondering if there is an alternative of str.substring() in string.h. If not, what is an efficient alternative?
Assuming that we all agree that using c++ it is safer and more professional to use the standard library tools.
That said, if we're talking about C and not C++, this should be one of the ways to extract a substring with the "string.h" library:
#include <stdio.h>
#include <string.h>
int main() {
char test[] = "abcdef";
char subtext[3];
memcpy(subtext, &test[1], 2); //Result: "bc"
subtext[2] = '\0';
printf("%s", subtext);
return 0;
}
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How would you convert a hexadecimal string, like "661efdf2e3b19f7c045f15" to the decimal string "123456789123456789123456789"?
Thanks in advance!
Using GMP you can assign the hex number to an "mpz_t" the GMP integer value. Here's an example.
#include <gmp.h>
int main(int argc, char** argv) {
mpz_t integer;
mpz_init(integer);
mpz_set_str(integer, "661efdf2e3b19f7c045f15", 16); //16 is the number base
gmp_printf("Your number is: %Zd\n", integer); //Outputs "Your number is: 123456789123456789123456789"
return 0;
}
GMP comes automatically with some linux distros but if you don't have it, you can download it here.
Hope this helps!
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Can I make a float number in a C program always round up
You can use the ceil() function. For example:
#include <stdio.h>
#include <math.h>
int main () {
float val1 = 1.6;
printf ("Round up to %.1lf\n", ceil(val1));
return(0);
}
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How can a string like "EINVAL" be converted into EINVAL?
I have to convert a lot of macro string to their value, what can be done?
Here is the simplest method I can think of:
#include <errno.h>
if (!strcmp(str, "EINVAL"))
value = EINVAL;
No preprocessor trick can convert the string literal to the corresponding symbol.
But you can use the preprocessor to simplify a sequence of such tests:
value = 0;
#define conv(s) do { if (!strcmp(str, #s)) value = s; } while (0)
conv(EINVAL);
conv(ENOMEM);
conv(ERANGE);
conv(EINTR);
#undef conv
A usual, be careful with the preprocessor...
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I really don't understands this code:
#include <stdio.h>
int main (int argument c, char *argument v[])
{
return 0;
}
What does this code mean? How does it converts to other formation of coding?
This is (almost) the simplest C/C++ program. (It works for both languages.) It does nothing other than return 0, which signifies successful execution.
It should read
int main(int argc, char **argv)