Numerical value of a string

[jrfrago]

say I have a string myString("425"), how do I get the value 425 then store it as an int variable?

Thanks in advance.

[vlad from moscow]

You can use standard function std::stoi

[Dy7SLyTq]

the only thing i can think of is atoi but... wait string streams!!!
u can use string streams! sorry im just really tired right now and didnt think i would be able to come up with something better than atoi

[jrfrago]

thanks. atoi works but not with characters...
how do we convert characters to its values?

[Dy7SLyTq]

do you mean its ascii value?

[18hRX9L8]

You can use sscanf and scan for an int in the char array.

#include <cstdio>
#include <cstdlib>

int StringToInteger(char* s) {
	int result;
	char dummy;

	if (s == NULL) {
		printf("NULL string passed to StringToInteger");
		_Exit(1);
	}
	
	if (sscanf(s, " %d %c", &result, &dummy) != 1) {
		printf("StringToInteger called on illegal number %s", s);
		_Exit(2);
	}

	return (result);
}

int main(void) {
	printf("%s+1 = %d","100",StringToInteger("100")+1);
	getchar();
}

Oh. You want char to int? Here:

#include <cstdio>

int CharToInt(char ch) {
	return (ch>'9'||ch<'0')?-1:ch-48;
}

int main(void) {
	if(1 == CharToInt('1')) {
		printf("Yay, it works!");
	}
}

[Dy7SLyTq]

ok im confused. if you want want us offered why wont atoi work? i can make it work for me. and why not string streams?

[vlad from moscow]

@jrfrago

I pointed out you function std::stoi. What is the problem?

std::string myString("425");

std::cout << std::stoi( myString ) << std::endl;

[jrfrago]

stoi also works, now I want to get the value of the individual character myString[0], myString[1], myString[2].

Thank you for all of your responses.

[Dy7SLyTq]

ATOI!!!!!!!!

[18hRX9L8]

jrfrago wrote:

stoi also works, now I want to get the value of the individual character myString[0], myString[1], myString[2].

See the 2nd code piece of my post.

DTSCode wrote:

ATOI!!!!!!!!

Lol.

[Dy7SLyTq]

guys... dont reinvent the wheel! atoi does that!!!!

[jrfrago]

stoi and atoi work but not with characters...

thanks usandfriends for the code.

[Dy7SLyTq]

yes they do. what do you think they do?

atoi takes a character and turns it into an int

[18hRX9L8]

jrfrago wrote:

stoi and atoi work but not with characters...

I think you need to review stoi and atoi. Here are their links:
http://www.cplusplus.com/reference/string/stoi/
http://www.cplusplus.com/reference/cstdlib/atoi/

DTSCode wrote:

guys... dont reinvent the wheel! atoi does that!!!!

jrfrago wrote:

thanks usandfriends for the code.

Thanks, but I agree with DTSCode. Functions given in primary libraries are usually:
1. Very fast.
2. Light.
3. Easy to use.
Therefore, I advise against using my code and to stick with atoi. Please use the links I posted to learn about them and how to use them. (There are also prime examples at the bottom.)

[jrfrago]

atoi(mySting[0]) gives an error Error 2 error C2664: 'atoi' : cannot convert parameter 1 from 'char' to 'const char *'

but it works with strings...

[18hRX9L8]

@DTSCode @Usandfriends
I think we were thinking of the wrong functions. atoi and stoi do the same things.

@jrfrago
Okay, I understand your point. Continue using my function.
Good luck!

Ps: make sure you mark this thread as Solved.

[Dy7SLyTq]

it works for me

[18hRX9L8]

@DTSCode

Post your code up here.

[Dy7SLyTq]

hold on i need to complete a wow achievement real quick