Why doesn't this code simply print letters A to Z?
<?php
for ($i = 'a'; $i <= 'z'; $i++)
echo "$in";
This snippet gives the following output (newlines are replaced by spaces):
abcdefghijklmnopqrstu vwxyz aa ab ac ad ae af ag ah ai aj ak al am an ao ap aq ar as at au av aw ax ay az ba bb bc bd be bf bg bh bi bj bk bl bm bn bo bp bq br bs bt bu bv bw bx by bz ca cb cc cd ce cf cg ch ci cj ck cl cm cn co cp cq cr cs ct cu cv cw cx cy cz da db dc dd de df dg dh di dj dk dl dm dn do dp dq dr ds dt du dv dw dx dy dz ea eb ec ed ee ef eg eh ei ej ek el em en eo ep eq er es et eu ev ew ex... on to yz
From the docs:
PHP follows Perl's convention when dealing with arithmetic operations on character variables and not C's.
For example, in Perl 'Z'+1 turns into 'AA' , while in C 'Z'+1 turns into '[' ( ord('Z') == 90 , ord('[') == 91 ).
Note that character variables can be incremented but not decremented and even so only plain ASCII characters (az and AZ) are supported.
From Comments:-
It should also be noted that <= is a lexicographical comparison, so 'z'+1 ≤ 'z' . (Since 'z'+1 = 'aa' ≤ 'z' . But 'za' ≤ 'z' is the first time the comparison is false.) Breaking when $i == 'z' would work, for instance.
Example here.
Because once 'z' is reached (and this is a valid result within your range, the $i++ increments it to the next value in sequence), the next value will be 'aa'; and alphabetically, 'aa' is < 'z', so the comparison is never met
for ($i = 'a'; $i != 'aa'; $i++)
echo "$in";
Others answers explain the observed behavior of the posted code. Here is one way to do what you want (and it's cleaner code, IMO):
foreach (range('a', 'z') as $i)
echo "$in";
In response to ShreevatsaR's comment/question about the range function: Yes, it produces the "right endpoint", ie the values passed to the function are in the range. To illustrate, the output from the above code was:
a
b
c
d
e
f
g
h
i
j
k
l
m
n
o
p
q
r
s
t
u
v
w
x
y
z
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