Wrong value assigned to variable - tsql

Question

I've started drafting a scalar function in SSMS 2012 to take a string and swap any occurrence of 3 hex URL characters (%2b, %2f and %3d) with their respective single character (-, / and =):
DECLARE #OutputText as VARCHAR(100)
DECLARE #c as Int
DECLARE #cIn as CHAR(3)
DECLARE #cOut as CHAR(1)
DECLARE #s as Int
SET #OutputText = '%2bBWCq6sE7OU%3d'
SET #c = 1
WHILE #c <= 3
BEGIN
-- Set the search/replace characters depending on iteration
IF #c = 1
SET #cIn = '%2b'
SET #cOut = '-';
IF #c = 2
SET #cIn = '%2f'
SET #cOut = '/';
IF #c = 3
SET #cIn = '%3d'
SET #cOut = '=';
SET #s = PATINDEX('%' + #cIn +'%', #OutputText)
WHILE #s > 0
BEGIN
PRINT 'Character Loop: ' + CAST(#c as VARCHAR(1)) + ' | looking for ' + #cIn + ' within ' + #OutputText
PRINT '(Replace ' + #cIn + ' with ' + #cOut + ')'
PRINT '-- ' + #cIn + ' found at position: ' + CAST(#s as VARCHAR(2))
SET #OutputText = STUFF(#OutputText, PATINDEX('%' + #cIn +'%', #OutputText) - 1, 3, #cOut)
PRINT '>> OutputText now: ' + #OutputText + CHAR(10)
SET #s = PATINDEX('%' + #cIn +'%', #OutputText)
END
SET #c = #c + 1
END
PRINT 'Final output: ' + #OutputText
The various PRINTs return this:
Notice the first character loop output says Replace %2b with = ... yet the if statement should be setting #cOut to - not = when #c = 1.
Another minor issue is that where the output says %2b found at position: the position number given seems 1 higher than it should be, like it's ignoring % of #cIn.

Answer 1

In your If statements, each setting of #cout will happen because they are not part of the IF. Only the next line after the IF executes. You need to wrap them in Begin End:
IF #c = 1
begin
SET #cIn = '%2b'
SET #cOut = '-'
end
else IF #c = 2
begin
SET #cIn = '%2f'
SET #cOut = '/'
end
else IF #c = 3
begin
SET #cIn = '%3d'
SET #cOut = '='
end
To prove this:
declare #thing int = 2
if #thing=1
select 'ralph'
select 'charles'
if #thing = 2
select 'ralph2'
select 'charles2'
This will produce charles, ralph2, charles2
Whereas this (with begin end):
declare #thing int = 2
if #thing=1
begin
select 'ralph'
select 'charles'
end
if #thing = 2
begin
select 'ralph2'
select 'charles2'
end
will correctly produce ralph2, charles2