# Hexadacimal To Decimal Program In C

Finding that a given number is even or odd, is a classic C program. We shall learn the use of conditional statement `if-else` in C.

## Algorithm

Algorithm of this program is very easy −

```START

Step 1 → Take integer variable A

Step 2 → Assign value to the variable

Step 3 → Perform A modulo 2 and check result if output is 0

Step 4 → If true print A is even

Step 5 → If false print A is odd

STOP
```

## Flow Diagram

We can draw a flow diagram for this program as given below −

## Pseudocode

```procedure even_odd()

IF (number modulo 2) equals to 0
PRINT number is even
ELSE
PRINT number is odd
END IF

end procedure
```

## 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;
}

int hexa2decimal(char n[])
{
int i,decimal,mul=0;

for(decimal=0,i=string_length(n)-1;i>=0;--i,mul+=4)
if(n[i]>='0' && n[i]<='9')
decimal+=(n[i]-48)*(1<<mul);
else if(n[i]=='A')
decimal+=10*(1<<mul);
else if(n[i]=='B')
decimal+=11*(1<<mul);
else if(n[i]=='C')
decimal+=12*(1<<mul);
else if(n[i]=='D')
decimal+=13*(1<<mul);
else if(n[i]=='E')
decimal+=14*(1<<mul);
else if(n[i]=='F')
decimal+=15*(1<mul);

return decimal;
}

int main()
{
char n[50];
int i,decimal,mul=0;

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

printf("Decimal equivalent is : %d",hexa2decimal(n));
return 0;
}

```

## Output

Output of the program should be −

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