How to increment a letter N times per iteration and store in an array?

Question

$letter = array();
for ($i = 'A'; $i !== 'ZZ'; $i++){
        $letter[] .= $i;
}
print_r($letter);

From above script I do a loop from A, B, C, D ... ZZ.

Now, I want to make it as A, C, E, G, I ... ZZ. (2 steps instead of 1)

I need direction to do it.

Solution 1

ord() will not work because your end string is two characters long.

Returns the ASCII value of the first character of string.

Watch it break.

From my testing, you need to check that the end string doesn't get "stepped over". The perl-style character incrementation is a cool method, but it is a single-stepping method. For this reason, an inner loop helps it along when necessary. This is actually not a bother, in fact, it is useful because we need to check if the loop(s) should be broken on each single step.

Code: (Demo)

function excelCols($letter,$end,$step=1){  // function doesn't check that $end is "later" than $letter
    if($step==0)return [];  // prevent infinite loop
    do{
        $letters[]=$letter;  // store letter
        for($x=0; $x<$step; ++$x){  // increment in accordance with $step declaration
            if($letter===$end)break(2);  // break if end is "stepped on"
            ++$letter;
        }
    }while(true);
    return $letters;    
}
echo implode(' ',excelCols('A','JJ',4));
echo "\n --- \n";
echo implode(' ',excelCols('A','BB',3));
echo "\n --- \n";
echo implode(' ',excelCols('A','ZZ',1));
echo "\n --- \n";
echo implode(' ',excelCols('A','ZZ',3));

Output:

A E I M Q U Y AC AG AK AO AS AW BA BE BI BM BQ BU BY CC CG CK CO CS CW DA DE DI DM DQ DU DY EC EG EK EO ES EW FA FE FI FM FQ FU FY GC GG GK GO GS GW HA HE HI HM HQ HU HY IC IG IK IO IS IW JA JE JI
 --- 
A D G J M P S V Y AB AE AH AK AN AQ AT AW AZ
 --- 
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 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 EY EZ FA FB FC FD FE FF FG FH FI FJ FK FL FM FN FO FP FQ FR FS FT FU FV FW FX FY FZ GA GB GC GD GE GF GG GH GI GJ GK GL GM GN GO GP GQ GR GS GT GU GV GW GX GY GZ HA HB HC HD HE HF HG HH HI HJ HK HL HM HN HO HP HQ HR HS HT HU HV HW HX HY HZ IA IB IC ID IE IF IG IH II IJ IK IL IM IN IO IP IQ IR IS IT IU IV IW IX IY IZ JA JB JC JD JE JF JG JH JI JJ JK JL JM JN JO JP JQ JR JS JT JU JV JW JX JY JZ KA KB KC KD KE KF KG KH KI KJ KK KL KM KN KO KP KQ KR KS KT KU KV KW KX KY KZ LA LB LC LD LE LF LG LH LI LJ LK LL LM LN LO LP LQ LR LS LT LU LV LW LX LY LZ MA MB MC MD ME MF MG MH MI MJ MK ML MM MN MO MP MQ MR MS MT MU MV MW MX MY MZ NA NB NC ND NE NF NG NH NI NJ NK NL NM NN NO NP NQ NR NS NT NU NV NW NX NY NZ OA OB OC OD OE OF OG OH OI OJ OK OL OM ON OO OP OQ OR OS OT OU OV OW OX OY OZ PA PB PC PD PE PF PG PH PI PJ PK PL PM PN PO PP PQ PR PS PT PU PV PW PX PY PZ QA QB QC QD QE QF QG QH QI QJ QK QL QM QN QO QP QQ QR QS QT QU QV QW QX QY QZ RA RB RC RD RE RF RG RH RI RJ RK RL RM RN RO RP RQ RR RS RT RU RV RW RX RY RZ SA SB SC SD SE SF SG SH SI SJ SK SL SM SN SO SP SQ SR SS ST SU SV SW SX SY SZ TA TB TC TD TE TF TG TH TI TJ TK TL TM TN TO TP TQ TR TS TT TU TV TW TX TY TZ UA UB UC UD UE UF UG UH UI UJ UK UL UM UN UO UP UQ UR US UT UU UV UW UX UY UZ VA VB VC VD VE VF VG VH VI VJ VK VL VM VN VO VP VQ VR VS VT VU VV VW VX VY VZ WA WB WC WD WE WF WG WH WI WJ WK WL WM WN WO WP WQ WR WS WT WU WV WW WX WY WZ XA XB XC XD XE XF XG XH XI XJ XK XL XM XN XO XP XQ XR XS XT XU XV XW XX XY XZ YA YB YC YD YE YF YG YH YI YJ YK YL YM YN YO YP YQ YR YS YT YU YV YW YX YY YZ ZA ZB ZC ZD ZE ZF ZG ZH ZI ZJ ZK ZL ZM ZN ZO ZP ZQ ZR ZS ZT ZU ZV ZW ZX ZY ZZ
 --- 
A D G J M P S V Y AB AE AH AK AN AQ AT AW AZ BC BF BI BL BO BR BU BX CA CD CG CJ CM CP CS CV CY DB DE DH DK DN DQ DT DW DZ EC EF EI EL EO ER EU EX FA FD FG FJ FM FP FS FV FY GB GE GH GK GN GQ GT GW GZ HC HF HI HL HO HR HU HX IA ID IG IJ IM IP IS IV IY JB JE JH JK JN JQ JT JW JZ KC KF KI KL KO KR KU KX LA LD LG LJ LM LP LS LV LY MB ME MH MK MN MQ MT MW MZ NC NF NI NL NO NR NU NX OA OD OG OJ OM OP OS OV OY PB PE PH PK PN PQ PT PW PZ QC QF QI QL QO QR QU QX RA RD RG RJ RM RP RS RV RY SB SE SH SK SN SQ ST SW SZ TC TF TI TL TO TR TU TX UA UD UG UJ UM UP US UV UY VB VE VH VK VN VQ VT VW VZ WC WF WI WL WO WR WU WX XA XD XG XJ XM XP XS XV XY YB YE YH YK YN YQ YT YW YZ ZC ZF ZI ZL ZO ZR ZU ZX

---

Here is an array-functions approach:

Code: (Demo)

$start='C';
$end='DD';
$step=4;

// generate and store more than we need (this is an obvious method disadvantage)
$result=$array=range('A','Z',1);  // store A - Z as $array and $result
foreach($array as $a){
    foreach($array as $b){
        $result[]="$a$b";  // store double letter combinations
        if(in_array($end,$result)){break(2);}  // stop asap
    }
}
//echo implode(' ',$result),"\n\n";

// slice away from the front of the array
$result=array_slice($result,array_search($start,$result));  // reindex keys
//echo implode(' ',$result),"\n\n";

 // punch out elements that are not "stepped on"
$result=array_filter($result,function($k)use($step){return $k%$step==0;},ARRAY_FILTER_USE_KEY); // use modulo

// result is ready
echo implode(' ',$result);

Output:

C G K O S W AA AE AI AM AQ AU AY BC BG BK BO BS BW CA CE CI CM CQ CU CY DC

Solution 2

Here is your solution for the problem,

$letter = array();
for ($i = 'A'; $i !== 'ZZ'; $i++){
        if(ord($i) % 2 != 0)
           $letter[] .= $i;
}
print_r($letter);

You need to get the ASCII value for that character which will solve your problem.

Here is ord doc and working code.

For your requirement, you can do like this,

for ($i = 'A'; $i !== 'ZZ'; ord($i)+$x){
  $letter[] .= $i;
}
print_r($letter);

Here set $x as per your requirement.

Comments

[Sahil Gulati]

loop from A, B, C, D to ZZ when ZZ will come.

[Mr Pro Pop]

I would say make an array of odd letters like 1 is A 3 is c etc..

[Ashok Kumar Sahoo]

try i++ twice instead of once

[mickmackusa]

Related (but not a duplicate as the answer is not found on the page): stackoverflow.com/questions/14278603/php-range-from-a-to-zz and stackoverflow.com/questions/27003100/…

[mickmackusa]

There is a lot of upvotes on Rahul's answer but it seems that no one bothered to test the method first. It breaks.

[Rahul]

@mickmackusa : For your information. OP doesn't mentioned he wants range as dynamic. That's why Sahil upvoted me. And when I answered, then OP specified that he wanted range as dynamic. That's correction for your blame. Thank you!

[mickmackusa]

@RahulMeshram Your methods break. Scroll all the way down to the bottom of your output array in your demo. Notice that Z_ never happens. You're welcome.

[Willy Mularto]

Thanks but it only works A, C, E.. Can we make it as dynamic as possible? Such a 3 steps, 5 steps, x steps? Thanks

[mickmackusa]

Your working code is not working. ord() cannot be used the way you are using it.

[Willy Mularto]

Wow it's very helpful code. FYI it requires at least PHP 5.4