# Octal To Binary program in C

## Implementation

Implementation of this algorithm is given below −

```
#include <stdio.h>

int string_length(char s[])
{
int i=0;

while(s[i]!='\0')
i++;

return i;
}

void string_reverse(char s[])
{
char *t;
for(t=s+string_length(s)-1;s<t;++s,--t) {
char temp=*s; *s=*t; *t=temp;
}
}

int binary2decimal(char n[])
{
int i,decimal,mul=0;

for(decimal=0,i=string_length(n)-1;i>=0;--i,++mul)
decimal+=(n[i]-48)*(1<<mul);

return decimal;
}

void printHexDigit(int d)
{
if(d<10) printf("%d",d);
else if(d==10) printf("A");
else if(d==11) printf("B");
else if(d==12) printf("C");
else if(d==13) printf("D");
else if(d==14) printf("E");
else if(d==15) printf("F");
}

int main()
{   char n[10],bits[100],temp[5];
int i,j,d;

printf("Enter a octal number : ");
scanf("%s",n);

string_reverse(n);

for(i=j=0;n[i]!='\0';++i)
for(d=n[i]-48;d!=0;d/=2)
bits[j++]=d%2+48;

bits[j]='\0';

string_reverse(bits);

for(i=j=0;i<string_length(bits)%4;++i,++j)
temp[j]=n[i];
temp[j]='\0';

printf("Hexa equivalent is : ");

d=binary2decimal(temp);
if(d!=0) printHexDigit(d);

while(bits[i]!='\0')
{
for(j=0;j<4;++i,++j)
temp[j]=bits[i];
temp[j]='\0';

d=binary2decimal(temp);
printHexDigit(d);
}
return 0;
}

```

## Output

Output of the program should be −

```24 is even
31 is odd
```