Assuming you're talking about C code...
Quote:
1) The number 27 and 156 are both octal, how do I add the two to where the result will be octal and not decimal which is 183.
a = 27 + 156
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By specifying them as octal numbers by prefixing the numbers with a zero ('0'). Like this:
a = 027 + 0156;
if you also want to print the result as an octal number use %o in the printf:
printf("%o\n", a);
Quote:
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2) What function do I use to convert a number to binary, octal, and hexadecimal.
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To specify a integer constant inside the C-code, prefix with '0' for octal, '0x' or '0X' for hexadecimal, and binary is not possible (in C).
To convert an integer to a string as octal or hexadecimal:
Code:
#include <stdio.h>
#define LEN 10
int a;
char str[LEN+1];
a = 123;
snprintf(str, LEN, "%o", a); /* str gets octal representation of a */
snprintf(str, LEN, "%X", a); /* str gets hexadecimal representation of a */
To get a string in binary is not possible directly (in C) as far as I know. But you can use this function:
Code:
#define NUMBITS 16
/* make sure str can store at least NUMBITS+1 char's
for example: char str[NUMBITS+1];
*/
void strbinary(char *str, int x)
{
int i;
for (i = 0; i < NUMBITS; ++i) str[NUMBITS-i-1]=x&1<<i?'1':'0';
str[NUMBITS] = '\0';
}
To read an integer from a string representing a dec, hex, oct or bin number:
Code:
#include <stdio.h>
#include <stdlib.h>
int main()
{
int a;
/* The strings below all represent (decimal) 123. */
a = (int)strtol("123", NULL, 10); /* str is decimal (base 10) */
printf("%d\n", a);
a = (int)strtol("1111011", NULL, 2); /* str is binary (base 2) */
printf("%d\n", a);
a = (int)strtol("173", NULL, 8); /* str is octal (base 8) */
printf("%d\n", a);
a = (int)strtol("7B", NULL, 16); /* str is hexadeciaml (base 16) */
printf("%d\n", a);
return 0;
}
Quote:
3) The function below convert an octal to string, but what is the function that convert a number to octal ?
single_char = strtoul (three_oct_char, NULL, 8);
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Do you mean: how to print a integer (or single char for that matter) as an octal number? or how to convert an integer to string as octal?
Use printf() or snprintf() for this. See above how.
