Header ("location" $url) cannot be used in an if statement

Header ("location". $url) cannot be used in an if statement?
Header ("location". $url) cannot be used in if statement does not take effect
What are the general non-effective situations? PHP header ()

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Where's the colon? Where is it?
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The bottom of the
if ($mhavelogin ==1) {header ("Location:". $GameLoginUrl);} else{?> You have not landed, please login first

Change into

if ($mhavelogin ==1) {header ("Location:". $GameLoginUrl);} else{Echo ' You have not landed, please log in first ';}

Specific reasons you Baidu find out about the use of the header function to pay attention to the place it
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Writing PHP Code I hope you're in some places you're strict with yourself

Cannot have output before header

Some UTF8 format is not available in front of BOM

There is, jump can be JS implementation

echo "";
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Put the header ("content-type:text/html; Charset=utf-8 "); Move to else, all jump, what's the use of this?
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Reference:

Reference: Put the header ("content-type:text/html; Charset=utf-8 "); Move to else, all jump, what's the use of this?
This is a login interface, want to click the login button to jump directly

I mean, you jump, you don't have to export any more headers.

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