I suck at coding need some help

Okay, so I have to make a code in python that converts from decimal to binary decimal to hexadecimal and lastly from binary to decimal. This is what I have so far:

Decimal to binary

 Spoiler

# convert a decimal to binary

def Denary2Binary(n):
'''convert denary integer n to binary string bStr'''
bStr = ''
if n < 0: raise ValueError, "must be a positive integer"
if n == 0: return '0'
while n > 0:
bStr = str(n % 2) + bStr
n = n >> 1
return bStr
def int2bin(n, count=24):
"""returns the binary of integer n, using count number of digits"""
return "".join([str((n >> y) & 1) for y in range(count-1, -1, -1)])

if __name__ == '__main__':
print Denary2Binary(255)
print int(Denary2Binary(255), 2)
print

print int2bin(255, 12)

print int("000011111111", 2)
print

print Denary2Binary(0)
print Denary2Binary(-5)

decimal to hexadecimal

 Spoiler

#converting decimal to hexdecimal
def decToHex():
#Get number from user
number=int(input("enter a postive number ")
if(number is<= 0)
0)
print("enter a postive number")
if(number=0)
print("the hexadecimal value of 0 equals 0")
else
hstr=" "
q=number
while(q>0):
if(q%16<10):
hstr=str(q%16)+hstr
elif(q%16==10):
hstr="A"+hstr
elif(q%16==11):
hstr="B"+hstr
elif(q%16==12):
hstr="C"+hstr
elif(q%16==13):
hstr="D"+hstr
elif(q%16==14):
hstr="E"+hstr
elif(q%16==15):
else:
hstr="F"+hstr
q=q//16
print(number, "converted to hexadecimal is " , hstr)

Binary to decimal

 Spoiler

def decimal_to_binary(arr,decimal):
if decimal ==1:
arr.append(1)
else:
rem = decimal%2
arr.append(rem)
rev = decimal/2
decimal_to_binary(arr,rev)
string
for i in arr[::-1]:
string+=str(i)
return string

I try to run these and I keep getting syntax errors so the program won't run and I have no idea how to fix them. So could anyone help me correct them not necessarily do them for me but at least give me a better explanation of where the errors are and what to do to fix them any help at all would be appreciated I'm at my wits end here.