Programming Forums > Application Development > C

amstu · Sep 7th, 2008, 1:51 PM

Is there an easy way to split an integer into an array?

I am able to do it, but the way I have it set up takes up way too many lines of code, and is not too flexible for integers of different lengths.

If anyone knows a relatively simple way to do this I would really appreciate the help.

Sane · Sep 7th, 2008, 3:17 PM

What do you mean by split an integer into an array? Do you mean turn each digit into a character or number in an array?

 C Syntax (Toggle Plain Text) 
#include <stdio.h>
 
int main() {
    int i, x = 501234900;
    char num[100];
    sprintf(num, "%d", x);
 
    for(i=0; num[i] != '\0'; i++) {
        printf("Digit %d = %d\n", i+1, num[i]-'0');
    }
 
    return 0;
}
#include <stdio.h>

int main() {
    int i, x = 501234900;
    char num[100];
    sprintf(num, "%d", x);
    
    for(i=0; num[i] != '\0'; i++) {
        printf("Digit %d = %d\n", i+1, num[i]-'0');
    }

    return 0;
}

Like that?

amstu · Sep 7th, 2008, 3:21 PM

Yes. I just need to turn each digit in the number into a number element in an array.

Sane · Sep 7th, 2008, 3:26 PM

Well there you go sir.

amstu · Sep 7th, 2008, 3:29 PM

I am trying to understand what you did. I get most of it but have 2 questions.

1. what is the sprintf command?

2. what does "num[1]!='\0'" state?

Sane · Sep 7th, 2008, 3:33 PM

sprintf is exactly like printf, except the output goes to a string instead of the standard output.

So after calling sprintf(num, "%d", x); the integer will be printed to the array "num".

num[i] != '\0' makes the loop go until the character is a "null-terminator" in the string (the character which marks the end of a string).

num[i] - '0' converts the character ('0' - '9') into an actual integer (0 - 9).

amstu · Sep 7th, 2008, 3:59 PM

I integrated that into my code and it works great. I have one last question, if you don't mind.

Everything works if the number is less than ten digits long. Is there anyway that I could make this work for number that have a length greater than 10 digits?

Thanks.

Sane · Sep 7th, 2008, 4:37 PM

An integer can only hold 32 bits, so its length is limited.

If the "integer" type is replaced with a "long long integer" you can get 64 bits of information and hold about 20 digits.

In many situations you can handle an integer with "infinite" digits (neglecting memory constraints) by simply using the array to start with. Where is the number coming from? Show us your code?

amstu · Sep 7th, 2008, 5:25 PM

The number is an input from the user.
The goal of my program is to take the input from the user and calculate the differences between each number in the array. (i.e. inputArray[4]={2,3,5,4} differenceArray[3]={1,2,-1})
Then it displays the results via "." and "@"

(Toggle Plain Text)

#import <Cocoa/Cocoa.h>

int main(int argc, char *argv[])
{
	int x=0;
	printf("Number? ");
	scanf("%i", &x);
	char num[100];
	int c=0;
	sprintf(num, "%i", x);
	
	for(int i=0;num[i]!='\0';i++){
		//printf("Digit %d=%d\n", i+1, num[i]-'0');
		c++;
	}
	int numArray[c];
	for(int i=0;num[i]!='\0';i++)
	{
		numArray[i]=num[i]-'0';
	}
	int difNumber[c-1];
	int new;
	
	
	for(int i=0;i<c-1;i++)
	{
		new=numArray[i+1]-numArray[i];
		difNumber[i]=new;
	}
	for(int i=0;i<c-1;i++)
	{
		printf("%i ", difNumber[i]);
	}
	printf("\n");
	for(int i=0;i<9;i++)
		printf("%i ", i-9);	
	for(int i=0;i<10;i++)
		printf("%i  ", i);
	printf("\n");
	for(int j=0;j<c-1;j++)
	{
		for(int i=0;i<19;i++)
		{
			int k=i-9;
			if(difNumber[j]==k)
			{
				printf("@  ");
				
			}
			else
			{
				printf(".  ");
			}
		}
		printf("\n");
	}	
}

Sane · Sep 7th, 2008, 6:30 PM

This sounds like homework so I won't code it for you. But a very quick and short solution does exist.

I would start by taking the input from the user in the form of a string:

 C Syntax (Toggle Plain Text) 
char buff[1024];
fgets(buff, sizeof(buff), stdin);
// Loop through digits of buff here
char buff[1024];
fgets(buff, sizeof(buff), stdin);
// Loop through digits of buff here

That way you don't even need to convert from integer to string. It will also give you "infinite" digits. Furthermore, if you do the looping intelligently, you will end up with a very short solution.

Sep 7th, 2008, 1:51 PM	#1
amstu Newbie Join Date: Sep 2008 Posts: 6 Rep Power: 0	splitting an integer into an array Is there an easy way to split an integer into an array? I am able to do it, but the way I have it set up takes up way too many lines of code, and is not too flexible for integers of different lengths. If anyone knows a relatively simple way to do this I would really appreciate the help.

Sep 7th, 2008, 3:17 PM	#2
Sane Programming Guru Join Date: Apr 2005 Location: Waterloo, Ontario Posts: 1,888 Rep Power: 5	Re: splitting an integer into an array What do you mean by split an integer into an array? Do you mean turn each digit into a character or number in an array? C Syntax (Toggle Plain Text) #include <stdio.h> int main() { int i, x = 501234900; char num[100]; sprintf(num, "%d", x); for(i=0; num[i] != '\0'; i++) { printf("Digit %d = %d\n", i+1, num[i]-'0'); } return 0; } #include <stdio.h> int main() { int i, x = 501234900; char num[100]; sprintf(num, "%d", x); for(i=0; num[i] != '\0'; i++) { printf("Digit %d = %d\n", i+1, num[i]-'0'); } return 0; } Like that? __________________ Waterloo's Canadian Computing Competition (CCC) - Stage 2 Problems, Solutions, and Test Data

Sep 7th, 2008, 3:21 PM	#3
amstu Newbie Join Date: Sep 2008 Posts: 6 Rep Power: 0	Re: splitting an integer into an array Yes. I just need to turn each digit in the number into a number element in an array.

Sep 7th, 2008, 3:26 PM	#4
Sane Programming Guru Join Date: Apr 2005 Location: Waterloo, Ontario Posts: 1,888 Rep Power: 5	Re: splitting an integer into an array Well there you go sir. __________________ Waterloo's Canadian Computing Competition (CCC) - Stage 2 Problems, Solutions, and Test Data

Sep 7th, 2008, 3:29 PM	#5
amstu Newbie Join Date: Sep 2008 Posts: 6 Rep Power: 0	Re: splitting an integer into an array I am trying to understand what you did. I get most of it but have 2 questions. 1. what is the sprintf command? 2. what does "num[1]!='\0'" state?

Sep 7th, 2008, 3:33 PM	#6
Sane Programming Guru Join Date: Apr 2005 Location: Waterloo, Ontario Posts: 1,888 Rep Power: 5	Re: splitting an integer into an array sprintf is exactly like printf, except the output goes to a string instead of the standard output. So after calling `sprintf(num, "%d", x);` the integer will be printed to the array "num". `num[i] != '\0'` makes the loop go until the character is a "null-terminator" in the string (the character which marks the end of a string). `num[i] - '0'` converts the character ('0' - '9') into an actual integer (0 - 9). __________________ Waterloo's Canadian Computing Competition (CCC) - Stage 2 Problems, Solutions, and Test Data

Sep 7th, 2008, 3:59 PM	#7
amstu Newbie Join Date: Sep 2008 Posts: 6 Rep Power: 0	Re: splitting an integer into an array I integrated that into my code and it works great. I have one last question, if you don't mind. Everything works if the number is less than ten digits long. Is there anyway that I could make this work for number that have a length greater than 10 digits? Thanks.

Sep 7th, 2008, 4:37 PM	#8
Sane Programming Guru Join Date: Apr 2005 Location: Waterloo, Ontario Posts: 1,888 Rep Power: 5	Re: splitting an integer into an array An integer can only hold 32 bits, so its length is limited. If the "integer" type is replaced with a "long long integer" you can get 64 bits of information and hold about 20 digits. In many situations you can handle an integer with "infinite" digits (neglecting memory constraints) by simply using the array to start with. Where is the number coming from? Show us your code? __________________ Waterloo's Canadian Computing Competition (CCC) - Stage 2 Problems, Solutions, and Test Data

Sep 7th, 2008, 5:25 PM	#9
amstu Newbie Join Date: Sep 2008 Posts: 6 Rep Power: 0	Re: splitting an integer into an array The number is an input from the user. The goal of my program is to take the input from the user and calculate the differences between each number in the array. (i.e. inputArray[4]={2,3,5,4} differenceArray[3]={1,2,-1}) Then it displays the results via "." and "@" (Toggle Plain Text) #import <Cocoa/Cocoa.h> int main(int argc, char argv[]) { int x=0; printf("Number? "); scanf("%i", &x); char num[100]; int c=0; sprintf(num, "%i", x); for(int i=0;num[i]!='\0';i++){ //printf("Digit %d=%d\n", i+1, num[i]-'0'); c++; } int numArray[c]; for(int i=0;num[i]!='\0';i++) { numArray[i]=num[i]-'0'; } int difNumber[c-1]; int new; for(int i=0;i<c-1;i++) { new=numArray[i+1]-numArray[i]; difNumber[i]=new; } for(int i=0;i<c-1;i++) { printf("%i ", difNumber[i]); } printf("\n"); for(int i=0;i<9;i++) printf("%i ", i-9); for(int i=0;i<10;i++) printf("%i ", i); printf("\n"); for(int j=0;j<c-1;j++) { for(int i=0;i<19;i++) { int k=i-9; if(difNumber[j]==k) { printf("@ "); } else { printf(". "); } } printf("\n"); } } #import <Cocoa/Cocoa.h> int main(int argc, char argv[]) { int x=0; printf("Number? "); scanf("%i", &x); char num[100]; int c=0; sprintf(num, "%i", x); for(int i=0;num[i]!='\0';i++){ //printf("Digit %d=%d\n", i+1, num[i]-'0'); c++; } int numArray[c]; for(int i=0;num[i]!='\0';i++) { numArray[i]=num[i]-'0'; } int difNumber[c-1]; int new; for(int i=0;i<c-1;i++) { new=numArray[i+1]-numArray[i]; difNumber[i]=new; } for(int i=0;i<c-1;i++) { printf("%i ", difNumber[i]); } printf("\n"); for(int i=0;i<9;i++) printf("%i ", i-9); for(int i=0;i<10;i++) printf("%i ", i); printf("\n"); for(int j=0;j<c-1;j++) { for(int i=0;i<19;i++) { int k=i-9; if(difNumber[j]==k) { printf("@ "); } else { printf(". "); } } printf("\n"); } }

Sep 7th, 2008, 6:30 PM	#10
Sane Programming Guru Join Date: Apr 2005 Location: Waterloo, Ontario Posts: 1,888 Rep Power: 5	Re: splitting an integer into an array This sounds like homework so I won't code it for you. But a very quick and short solution does exist. I would start by taking the input from the user in the form of a string: C Syntax (Toggle Plain Text) char buff[1024]; fgets(buff, sizeof(buff), stdin); // Loop through digits of buff here char buff[1024]; fgets(buff, sizeof(buff), stdin); // Loop through digits of buff here That way you don't even need to convert from integer to string. It will also give you "infinite" digits. Furthermore, if you do the looping intelligently, you will end up with a very short solution. __________________ Waterloo's Canadian Computing Competition (CCC) - Stage 2 Problems, Solutions, and Test Data

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Programming Forums > Application Development > C

splitting an integer into an array