Extract Two Float/Double Numbers Out of a String on C?

[TukangUsapEmenq]

As the tittle says, it is. Needs you guys references for extracting two float numbers (or integers, nah any kind of number) out of a string. Example, I type -2.2+3i and I need both of the real and imaginary number to be separated so I can use them for the operations.

 

Kinda new in programming, just by 2 months learning about C on campus, so yeah.

 

I'm stuck at here searching at everywhere.

Example (for program using command line argument tho): (it's in Indonesian but... You'll get the point from the inputs and outputs.)

Spoiler

 

Y'all help will be nicely appreciated, as deadline is 2 days away. (not only this tho, still a lot job to do)

[mariushm]

You're referring to command line arguments... which can be read a certain way :

 

See https://www.geeksforgeeks.org/command-line-arguments-in-c-cpp/

 

Each argument is a separat variable, you just have to convert them to float/decimal/int/whatever using other functions ... maybe atof or stof :

http://www.cplusplus.com/reference/cstdlib/atof/

http://www.cplusplus.com/reference/cstdlib/strtof/ (may not be available in plain c)

 

also it seems optional, but you may want to convert the first argument to lowercase and then use ifs or switch ex if operation == 'add' then ...

 

if you truly mean a string, i would look for the separator between the numbers ( +,-, etc) keeping in mind there may be a + or - in the variable ex 10e+2 so maybe look for [space][operation][space]

Remember the index in the string where the operation is found, then copy the characters before into a variable, and characters after into another.. then use existing conversion functions.

[TukangUsapEmenq]

13 minutes ago, mariushm said:

You're referring to command line arguments... which can be read a certain way :

 

See https://www.geeksforgeeks.org/command-line-arguments-in-c-cpp/

 

Each argument is a separat variable, you just have to convert them to float/decimal/int/whatever using other functions ... maybe atof or stof :

http://www.cplusplus.com/reference/cstdlib/atof/

http://www.cplusplus.com/reference/cstdlib/strtof/ (may not be available in plain c)

 

also it seems optional, but you may want to convert the first argument to lowercase and then use ifs or switch ex if operation == 'add' then ...

 

if you truly mean a string, i would look for the separator between the numbers ( +,-, etc) keeping in mind there may be a + or - in the variable ex 10e+2 so maybe look for [space][operation][space]

Remember the index in the string where the operation is found, then copy the characters before into a variable, and characters after into another.. then use existing conversion functions.

Quick one reply, thanks! That atof might be useful.

And yeah I really meant the string. Any kind of codes example for this? I learn much more easily if I read the codes directly.

[Unimportant]

2 hours ago, dhannemon13 said:

Needs you guys references for extracting two float numbers (or integers, nah any kind of number) out of a string.

#include <stdio.h>

int 
main(void)
{
	const char* exampleString = "-2.2+3i";

	double real;
	double im;
	if (sscanf(exampleString, "%*[^0123456789]%lf%*[^0123456789]%lf", &real, &im) != 2)
	{
		printf("Failed to extract real & im!\n");
		return 1;
	}
	printf("real: %lf, im: %lf\n", real, im);

	return 0;
}

 

[TukangUsapEmenq]

10 hours ago, Unimportant said:

#include <stdio.h>

int 
main(void)
{
	const char* exampleString = "-2.2+3i";

	double real;
	double im;
	if (sscanf(exampleString, "%*[^0123456789]%lf%*[^0123456789]%lf", &real, &im) != 2)
	{
		printf("Failed to extract real & im!\n");
		return 1;
	}
	printf("real: %lf, im: %lf\n", real, im);

	return 0;
}

 

Exactly what I need. Not yet functioning as intended, but thanks a lot!

 

EDIT: got it works. Might be useful for another beginners around here.

#include <stdio.h>

int main()
{
    double real;
	double im;
    char exampleString[20];

    scanf("%s",&exampleString);


	sscanf(exampleString, "%lf+%lf", &real, &im);

	printf("real: %f, im: %f\n", real, im);

	return 0;
}