String -> int

[Aske]

Hi, I'm having a problem for casting a string to int, so tht evry number in the string becomes a diff int. Cus I get wrong numbers back.

I'll post an example
its sumtin like this:
int main(void){

int x_rij, x_kolom, y_rij, y_kolom;
char spel_request[5];

scanf("%s",&spel_request);
if((int)spel_request != '0'){
x_rij= ((int)spel_request[0]);
x_kolom= ((int)spel_request[1]);
y_rij= ((int) spel_request[3]);
y_kolom=((int)spel_request[4]);
}
printf("\n %d\n %d\n %d\n %d",x_rij,x_kolom,y_rij,y_kolom);

return 0;
}

I'm not so good at this rly, just learning it.

Regards A.

[weaknessforcats]

You can't cast a string to an int.

A string is an array of char. Therefore, the name of the string is the address of element 0. When you cast, you are casting the address of the string to an int.

You will need to call a function to convert for you. Try atoi().

[oler1s]

Hi, I'm having a problem for casting a string to int

Casting in C is simple. I think you have it right. (type) variable is the syntax. But I highly doubt you want to cast. I think what you want is to convert the string into a number.

I'm trying to make a point here. I don't know how you got the idea into your head, but casting is not the same as converting. Casting overrides the compiler. You effectively say, this is a variable of one type, but I know so much better than you, and I'm telling you to pretend it's actually another type. Maybe your computer will explode because of that. Whatever. You get the gun, and you get to point it at your foot and pull the trigger. Don't complain.

There is a function in C for converting C strings to numbers. There's two actually. atoi and strtol. Don't use atoi. Use strtol. Google on how to do this.

[Aske]

kk, thx for response. Now I kno at least I'm not going the right way. Will look into the strtol() then.

ty

[Aske]

I don't know how you got the idea into your head, ...

well... the user has to input 4 ints vor ex: "12 34" and these numbers gotta have diffrent names, ex: x=1, y=2, etc... . I thought this was the way to do it, but silly me.

[oler1s]

Well, your idea could be made to work. But there are certain implications. Remember that in the end, everything is just 1s and 0s to the computer. Chars are 1s and 0s, and Cstrings are arrays of chars. So you could technically cast a char as an int.

Let me ask you a question. Convert 'a' to a number. Now convert 'b' to a number. You might say a=1 and b=2. Logical, right? What about a=20 and b=21? Well, that works too, right? How about a=31, b=32? Maybe a=33,b=35,c=37? This mapping of numbers to an alphabet is a Character encoding. ASCII is the most well known, but look at systems like EBCDIC and what not. It has g,h, and i in a row. But there's a gap between i and j, and so on. Technically, you could just pretend that ASCII is the only system in existence for your purposes, but you might as well learn to write robust code now, and then fool around later at your peril.

[Aske]

Got it kinda solved this way,
#include ...

int main(void){
char spel_request[5], *hulp;
int a[5], t;

clrscr();
scanf("%5[^\n]*s",&spel_request);
if(spel_request[0] == '0'){
printf("sluiten");
}else{
for (t=0;t<5;t++){
hulp = spel_request[t];
a[t] = atoi(&hulp);
printf("%c ", hulp);
}
printf("\n %d\n %d\n %d\n %d",a[0],a[1],a[3],a[4]);
}

return 0;
}

but the problem now is, when I input it into the program it gives an unending loop thx to scanf("%5[^\n]*s",&spel_request);

any thoughts?

Regards

[akuuu]

Here is a funtion that might do the job.
Returns the converted string

int a_to_i(char *s){
int i = 0, sign;
if(*s == '-'){
sign = -1;
s++;
}
else sign = 1;
while(isdigit(*s)){
i += *s -'0';
i*= 10;
s++;
}
return znak*i/10;
}

btw isdigit is standard function in C that checks if some element of the string is digit or '0' <= x[i] <= '9', ofc x[MAX] is string

[akuuu]

and i forgot u need another function that will turn the integer ex. 1234 to 4321. This looks like this

int reverse(int a)
{
int i;
while(a){
i = a%10;
a /= 10;
i *= 10;
}
return (i/10);
}


thats it.