C Programming Homework Help Needed

[bear24rw]

Originally Posted by Pat McCarthy

Back again!
I can't figure out how to convert a float value to a char string.
Suggestions? Thanks!

Like take value 9.023 and turn it into '9' '.' '0' '2' '3' in a char string?

Idk how you would get each number individually but to change the number into its ASCII code you would do
# + '0' to get the ascii code of the number

[Pat McCarthy]

Originally Posted by bear24rw

Like take value 9.023 and turn it into '9' '.' '0' '2' '3' in a char string?

Well, I have a float variable that I need to be able to display using WinBGI using the text function that only accepts char strings. So, I really don't know exactly.

[EricVanWyk]

The function you are looking for is called "sprintf".

Use it just like you would use printf to print a float. The trick is that it throws it into a string, rather than at the console.

char * buffer = new char[10];
float f = 12.4;
sprintf(buffer,"%f",f);

I think... I don't have a C compiler in front of me.

[Pat McCarthy]

Is there a header file you need to include?
I'm getting a 'no prototype for function' error for the sprintf function.

[chris31]

Originally Posted by Pat McCarthy

Is there a header file you need to include?
I'm getting a 'no prototype for function' error for the sprintf function.

I believe you need to include stdio.h.

[Pat McCarthy]

Originally Posted by chris31

I believe you need to include stdio.h.

That made that error go away but I still don't really understand how to use the function.
The first line:

char * buffer = new char[10];

is confusing me.

[eugenebrooks]

Originally Posted by Pat McCarthy

That made that error go away but I still don't really understand how to use the function.
The first line:

char * buffer = new char[10];

is confusing me.

The use of the "new" operator is C++ speak, not C speak.

char buffer[10]; /* bigger than 10 is a good idea */

If a static or automatic array (depending on the location
of the declaration) is good enough, or

char *buffer;

buffer = malloc(10); /* again, bigger than 10 is a good idea */

to allocate the storage using the heap allocator in C.

Eugene

[Pat McCarthy]

I am using this code:

#include <stdio.h>

int main(void)
{
	char *buffer;

	buffer = malloc(10);
	float f = 12.4;
	sprintf(buffer,"%f",f);

	return 0;
}

Attached is the compile errors I am getting.

[eugenebrooks]

Originally Posted by Pat McCarthy

I am using this code:

#include <stdio.h>

int main(void)
{
	char *buffer;

	buffer = malloc(10);
	float f = 12.4;
	sprintf(buffer,"%f",f);

	return 0;
}

Attached is the compile errors I am getting.

malloc() is likely declared in stdlib.h

[Pat McCarthy]

Originally Posted by eugenebrooks

malloc() is likely declared in stdlib.h

It was. Thanks.

Now how can I use the char value?

I tried:
printf("%c", buffer);

But that printed out an an arrow pointing up.

[eugenebrooks]

Originally Posted by Pat McCarthy

It was. Thanks.

Now how can I use the char value?

I tried:
printf("%c", buffer);

But that printed out an an arrow pointing up.

The result of sprintf is a null, '\0', terminated string.

printf("%s", buffer);


printf("%c", buffer[0]);
would print the first char

Eugene

[Pat McCarthy]

Originally Posted by eugenebrooks

The result of sprintf is a null, '\0', terminated string.

printf("%s", buffer);


printf("%c", buffer[0]);
would print the first char

Eugene

Thanks! I think that should do it for this week!

[Astronouth7303]

Originally Posted by Pat McCarthy

It was. Thanks.

Now how can I use the char value?

I tried:
printf("%c", buffer);

But that printed out an an arrow pointing up.

If you just want to print the value of the float, skip the sprintf() call and go straight to printf():

float f = 12.4;
printf("%f",f);

The *printf() family of functions (sprintf(), fprintf(), printf(), etc.) all work similarly. Becoming familiar with them will help.

If you ever have a simple question about a function, Google is your friend. (Just put in the function name or "C functionName".) Even Wikipedia has an article about most standard functions.

[Pat McCarthy]

This code is supposed to convert a base 10 number, 123, into binary and display the value. Somewhere in the conversion, the division loop stops before it should, for a reason that I cannot identify.
Output with some diagnostic print statements attached.

/* Patrick McCarthy */

#include <stdio.h>
#include <math.h>

void base_convert(int base);
void convert_to_binary(int base, int number);
void divide(int D, int N, int *pq, int *pr);

int main(void)
{
	int base;
	int base_error;

	/* Gets the base from user and validates the value */
	do{
		base_error = 0;

		/* Collects base value from user */
		printf("Please enter an integer between 2 and 10 =>");
		fflush(stdin);
		scanf("%d",&base);

		/* Validate entry */
		switch (base)
		{
			case 2:
			case 3:
			case 4:
			case 5:
			case 6:
			case 7:
			case 8:
			case 9:
			case 10:
				break;
			default:
				base_error = 1;
				printf("Invalid entry\n");
		}
	}
	while(base_error);

	/* Finds base N value of NUMBER */
//	base_convert(base);

	/* Converts number to Binary */
	convert_to_binary(base, 123);

	return 0;
}

void base_convert(int base)
{
	int i;
	int new[3];
	int NUMBER[3];
	int answer;

	//The base 10 number to be converted
	NUMBER[0] = 3;
	NUMBER[1] = 2;
	NUMBER[2] = 1;

	for(i = 0; i < 3; i++)
	{
		new[i] = ( NUMBER[i] * pow(base,i) );

		// Diagnostic
//		printf("i = %d; NUMBER[i] = %d; new[i] = %d\n", i, NUMBER[i], new[i]);
	};

	answer = new[0] + new[1] + new[2];

	printf("%d%d%d(Base 10) = %d(Base %d)", NUMBER[2],NUMBER[1],NUMBER[0],answer, base);

	return;
}

void convert_to_binary(int base, int number)
{
	int j,h;
	int q[16];
	int r[16];

	q[0] = number;

	for(j = 1; q[j] >= 0; j++)
	{
		printf("j=%d\n",j);
		divide(base, q[j-1], &q[j], &r[j]);
	}

	for(h = j; h <= 0; h--)
	{
		printf("%d", r[h]);
	}
}

void divide(int D, int N, int *pq, int *pr)
{
	int q,r;

	q = N / D;
	r = N % D;
	
	printf("Quotient: %d\nRemainder: %d\n\n", q,r);

	*pq = q;
	*pr = r;
}

[StormRoBoT]

help on palindrome

i have make a program that can trace palindrome number but i need it to loop over and over again till i keyin -1 then only the program terminate


this is the code that i have used:

#include<stdio.h>
#include<string.h>

void main()
{
char strsrc[5];
char strtmp[5];

printf("\n Enter a five-digit number ( -1 to end ): "); gets(strsrc);

strcpy(strtmp,strsrc);
strrev(strtmp);

if(strcmp(strsrc,strtmp)==0)
printf("\n %s is a palindrome\n",strsrc);
else
printf("\n %s is not a palindrome\n",strsrc);
}

any one can help?