C language example 100 (IV)

33. Octal and binary conversion

33.1 Binary to octal

（1） Binary to octal The core yes ： Convert binary to decimal first , Convert to octal in .
（2） Use pow There was a problem with the function ： There are many. overloaded function “pow” The instance matches the parameter list . There are many. overloaded function “pow” The instance matches the parameter list :
function “pow(double _X, int _Y)”
function “pow(float _X, int _Y)”
function “pow(long double _X, int _Y)”
Parameter type is : (int, int)
That's because pow(） The return value of the function is double type .
So here pow(2.0,i) Can not write pow(2,i)
（3） Octal numbers have only 0-7; Decimal numbers have only 0-9; Binary numbers only 0-1.

（1） Code

#if 1
/* Binary to octal */
#include <stdio.h>
#include <windows.h>
#include <math.h>

int convertBinarytoOctal(long long binaryNumber)
{
    
	int octalNumber = 0;
	int decimalNumber = 0;
	int i = 0;
 
	// Convert binary to decimal 
    while(binaryNumber != 0)
	{
    
		// It must be written here pow(2.0,i), because pow() The return type of is double
		decimalNumber += (binaryNumber%10)*pow(2.0,i);// Get each bit in turn from the low position （ such as 11111%10 = 1）
        ++i;// Multiply sequentially 2^0、2^1、2^2、....
        binaryNumber/=10;// Eliminate every digit from the low order （11111/10 = 1111）
    }
	i = 1;
 
	// Convert decimal numbers to octal 
    while (decimalNumber != 0)
	{
    
		// ride i Because when decimal to octal , Short division , In reverse order . Multiply sequentially 1、10、100、1000...
		// Get the remainder 
		octalNumber += (decimalNumber % 8) * i;
		// Get divisor 
        decimalNumber /= 8;
        i *= 10;
    }
	return octalNumber;
}

int main()
{
    
	long long binaryNumber;
    printf(" Enter a binary number : ");
    scanf("%lld", &binaryNumber);
    printf(" Binary number  %lld  Convert to octal to  %d", binaryNumber, convertBinarytoOctal(binaryNumber));
	system("pause");
	return 0;
}
#endif

// Statement 
//33.1  Binary to octal 
int convertBinarytoOctal(long long binaryNumber);

（2） Running results

33.2 Octal to binary

Octal to binary The core yes ： First convert octal to decimal , Convert to binary .

（1） Code

#if 1
/*33.2  Octal to binary */
#include <stdio.h>
#include <windows.h>
#include <math.h>

long long convertOctalToBinary(int octalNumber)
{
    
	int decimalNumber = 0, i = 0;
    long long binaryNumber = 0;
 
	// Octal to decimal 
    while(octalNumber != 0)
	{
    
		decimalNumber += (octalNumber%10) * pow(8.0,i);
        ++i;
        octalNumber/=10;
    }

	// Convert decimal to binary 
	i = 1;	
    while (decimalNumber != 0)
	{
    
		binaryNumber += (decimalNumber % 2) * i;
        decimalNumber /= 2;
        i *= 10;
    }
	return binaryNumber;
}
int main()
{
    
	int octalNumber;
    printf(" Enter an octal number : ");
    scanf("%d", &octalNumber);
    printf(" Octal number  %d  Convert binary to  %lld\n", octalNumber, convertOctalToBinary(octalNumber));
	system("pause");
	return 0;
}
#endif

// Statement 
//33.2  Octal to binary 
long long convertOctalToBinary(int octalNumber);

（2） Running results

34. Octal and decimal conversion

34.1 Convert decimal to octal

（1） Code

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

int convertDecimalToOctal(int decimalNumber)
{
    
	int octalNumber = 0, i = 1;
 
    while (decimalNumber != 0)
	{
    
		octalNumber += (decimalNumber % 8) * i;
        decimalNumber /= 8;
        i *= 10;
    }
	return octalNumber;
}
int main()
{
    
	int decimalNumber;
    printf(" Enter a decimal number : ");
    scanf("%d", &decimalNumber); 
    printf(" Decimal number  %d  Convert to octal to  %d\n", decimalNumber, convertDecimalToOctal(decimalNumber));
    system("pause");
	return 0;
}

// Statement 
//34.1  Convert decimal to octal 
int convertDecimalToOctal(int decimalNumber);

（2） Running results

34.2 Binary to octal

（1） Code

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


long long convertOctalToDecimal(int octalNumber)
{
    
	int decimalNumber = 0, i = 0;
 
    while(octalNumber != 0)
	{
    
		decimalNumber += (octalNumber%10) * pow(8.0,i);
        ++i;
        octalNumber/=10;
    }
	i = 1;
    return decimalNumber;
}

int main()
{
    
	int octalNumber; 
    printf(" Enter an octal number : ");
    scanf("%d", &octalNumber); 
    printf(" Octal number  %d  Convert to decimal to  %lld\n", octalNumber, convertOctalToDecimal(octalNumber)); 
	system("pause");
    return 0;
}

// Statement 
long long convertOctalToDecimal(int octalNumber);//34.2  Octal to decimal 

（2） Running results

35. Binary and decimal conversion

35.1 Binary to decimal

（1） Code

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


int convertBinaryToDecimal(long long n)
{
    
	int decimalNumber = 0, i = 0, remainder;
    while (n!=0)
	{
    
		remainder = n%10;    
        decimalNumber += remainder*pow(2.0,i);
		n /= 10;
        ++i;
    }
	return decimalNumber;
}

int main()
{
    
	long long n;
    printf(" Enter a binary number : ");
    scanf("%lld", &n);
    printf(" Binary number  %lld  Convert to decimal to  %d\n", n, convertBinaryToDecimal(n));
	system("pause");
    return 0;
}

// Statement 
//35.1  Binary to decimal 
int convertBinaryToDecimal(long long n);

（2） Running results

35.2 Convert decimal to binary

（1） Code

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

#define _CRT_SECURE_NO_WARNINGS 0

long long convertDecimalToBinary(int n)
{
    
	long long binaryNumber = 0;
    int remainder, i = 1, step = 1;
 
    while (n!=0)
	{
    
		remainder = n%2;
        printf("Step %d: %d/2,  remainder  = %d,  merchant  = %d\n", step++, n, remainder, n/2);
        n /= 2;
        binaryNumber += remainder*i;
        i *= 10;
    }
		return binaryNumber;
}
int main()
{
    
	int n;
    printf(" Enter a decimal number : ");
    scanf("%d", &n);
    printf(" Decimal number  %d  Convert to binary  %lld\n", n, convertDecimalToBinary(n));
	system("pause");
    return 0;
}

// Statement 
//35.2  Convert decimal to binary 
long long convertDecimalToBinary(int n);

（2） Running results