用户输入两个单元格的php乘法

Question

for ($i=1; $i<=3; $i++) 
{
print("<tr>");
print("<td>$i</td>");

print("<td><input type='text' name='meter[$i]' class='meter' maxlength='21' id='meter[$i]' /></td>");
                    print("<td><input type='text' name='weight[$i]' maxlength='21' class='weight' id='weight[$i]' size='10' /></td>");
print("<td><input type='text' name='amount[$i]' maxlength='21' class='amount' id='amount[$i]' size='10' /></td>");                  
print("</tr>");
}
?>

i want like this

if i enter 110 in meter and 10 in weight it should give me ans (10/110)*100; in each column

(weight/meter)*100

  meter  weight  output
    110   | 10   |  9.09
    120   | 12   |  10
    130   | 14   |  10.76

Answer 1

One way to do this is by using a javascript code, so that the calculation is done locally in the browser's client, without the need to submit a form to the server:

<?php
print("<script>");
print("function calculate(index) {;");
print("     var meterd = document.getElementById('meter['+index+']');");
print("     var weightd = document.getElementById('weight['+index+']');");
print("     var amountd = document.getElementById('amount['+index+']');");
print("     if (meterd && weightd && amountd) {;");
print("         var meter = parseFloat(meterd.value); if (isNaN(meter)) {meter = 1;}");
print("         var weight = parseFloat(weightd.value); if (isNaN(weight)) {weight = 0;}");
print("         amountd.value = weight * 100 / meter;");
print("     };");
print("};");
print("</script>");

print("<table>");
for ($i=1; $i<=3; $i++) 
{
    print("<tr>");
    print("<td>$i</td>");
    print("<td><input type='text' name='meter[$i]' class='meter' maxlength='21' id='meter[$i]' onkeyup='calculate($i)'/></td>");
    print("<td><input type='text' name='weight[$i]' maxlength='21' class='weight' id='weight[$i]' size='10' onkeyup='calculate($i)'/></td>");
    print("<td><input type='text' name='amount[$i]' maxlength='21' class='amount' id='amount[$i]' size='10' /></td>");                  
    print("</tr>");
}
print("</table>");
?>

Tested, it worked for me.