Understand PHP for loop

Question

for ($i=1; $i<=4; ++$i) {
    echo "The number is " . $i . "\n";
}

This will output:

The number is 1
The number is 2
The number is 3
The number is 4

How can i make a loop that will give me output like so:

The number is 1
The number is 1
The number is 1
The number is 1
The number is 2
The number is 2
The number is 2
The number is 2
etc

Thanks for any help.

Not sure why there are down votes. This seems to be a legitimate beginner question. Some constructive criticism would be helpful on downvotes. +1 to offset the negativity. — kingjeffrey
– kingjeffrey, Commented Jun 29, 2012 at 23:40
@kingjeffrey I hate it when people downvote without leaving a comment... Apart from being a legitimate beginner question, it was well formed and clearly presented. — sachleen
– sachleen, Commented Jun 29, 2012 at 23:44

ikegami · Accepted Answer · 2012-06-29 23:44:01Z

7

Without nested loops: this would suffice for a single loop.

for($i=0;$i<9*4;$i++)
{
    echo "The number is ".(1+floor($i/4));
}

edited Jun 29, 2012 at 23:44

ikegami

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answered Jun 29, 2012 at 23:36

Wampie Driessen

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6 Comments

Dai Over a year ago

Clever! I like the way you think.

ikegami Over a year ago

Using floating pointer for your iterator is a bad idea. It can lead to weird numbers and incorrect number of iterations. I hope you don't mind my fix.

ikegami Over a year ago

This non-nested approach is useful if you want to limit the total number of lines independently of the number of message repeats. When the bound is a multiple of the number message repeats, a nested loop is clearer.

rid Over a year ago

@ikegami, and more efficient, too. Increasing a long int is much faster than running a function that takes a double as argument and produces a double as result, passing it the result of a floating point operation and casting the result to a long int.

kingjeffrey Over a year ago

@ikegami's edits may have fixed issues in this answer, but it also made it significantly more opaque. I thought the original answer was clever, but with this fix, I prefer the nested loop solution.

|

ikegami · Accepted Answer · 2012-06-29 23:37:54Z

4

So you want

for ($i=1; $i<=2; ++$i) {
    echo "The number is " . $i . "\n";
    echo "The number is " . $i . "\n";
    echo "The number is " . $i . "\n";
    echo "The number is " . $i . "\n";
}

But let's avoid the repetition with a loop!

for ($i=1; $i<=2; ++$i) {
    for ($j=1; $j<=4; ++$j) {
        echo "The number is " . $i . "\n";
    }
}

answered Jun 29, 2012 at 23:37

ikegami

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2 Comments

kingjeffrey Over a year ago

+1 for the repetitive echos. It is bad form, but proves the need for the inner loop.

ikegami Over a year ago

@kingjeffrey, Thanks. Nested loops can be daunting to newcomers, so I wanted to show the process that leads to using it instead of jumping to the answer.

sachleen · Accepted Answer · 2012-06-29 23:38:03Z

3

Essentially, you want to print something four times inside the loop... so you can write four echo statements. A better way to do this would be to use nested for loops.

for ($i=1; $i<=4; ++$i) {
    for ($j=1; $j<=4; ++$j) {
        echo "The number is " . $i . "\n";
    }
}

For every iteration of the outer loop, the inner one prints the statement four times. One thing to be careful with nested loops is the variables used in the conditions. If you mix them up, you could have weird issues including an infinite loop.

answered Jun 29, 2012 at 23:38

sachleen

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Comments

nickb · Accepted Answer · 2012-06-29 23:36:59Z

3

You need two nested loops, like so:

for( $i = 1; $i <= 4; ++$i) { 
    for( $j = 1; $j <= 4; ++$j) {
        echo "The number is " . $i . "\n"; 
    }
}

edited Jun 29, 2012 at 23:36

answered Jun 29, 2012 at 23:36

nickb

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Comments

Wh1T3h4Ck5 · Accepted Answer · 2012-07-02 03:37:27Z

3

One of a million of possible solutions could be using single loop and str_repeat() function.

for ($i=1; $i<=4; $i++)
  echo str_repeat("The number is $i\n", 4);

which is probably the best way to make multiple repeats of same string.

edited Jul 2, 2012 at 3:37

answered Jun 30, 2012 at 0:00

Wh1T3h4Ck5

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Comments

ahmetunal · Accepted Answer · 2012-06-29 23:36:59Z

2

you can make two loops

for($i = 1; $i <= 4; $i++) {
    for($j = 1; $j <= 4; $j++) {
        echo 'The number is '.$i."\n";
    }
}

answered Jun 29, 2012 at 23:36

ahmetunal

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Comments

Dai · Accepted Answer · 2012-06-29 23:36:42Z

1

You've got the same loop, but four iterations within:

for ($i=1; $i<=4; ++$i) {
    for($j=0;$j<4;$j++) {
        echo "The number is " . $i . "\n";
    }
}

answered Jun 29, 2012 at 23:36

Dai

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