Constant are identifiers for a memory location Which Can be change according to requirement of program .In PHP <\/a> Constant does NOT support interpolation <\/a>. In PHP <\/a>Constant must be in Upper Case eg. CONST \u00a0.<\/strong>To define Constant we have to use function define();<\/p>\n Syntax : NOTE:Unlike variable \u00a0If we Try to define same Constant again then it throw a notice Already define.<\/p>\n <\/p>\n Another way of Defining Constant is key word const <\/strong>.<\/p>\n eg:\u00a0 <\/span>const <\/span>MIN_VALUE <\/span>= <\/span>0.0;<\/span><\/p>\n echo\u00a0\u00a0 <\/span>MIN_VALUE ;\u00a0\/\/\/ will result to\u00a00<\/span><\/p>\n <\/p>\n The fundamental difference between those two ways is that const<\/strong> defines constants at compile time<\/strong>, whereas define<\/strong> defines them at run time<\/strong>.<\/p>\n Note : const cannot be used to conditionally define constants. It has to be used in the outermost scope<\/strong><\/p>\n eg:<\/p>\n <?php<\/p>\n $x=10 and $y=10; ?><\/p>\n","protected":false},"excerpt":{"rendered":" Constant in PHP ? 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\ndefine(\\’name of constant \\’,\\’ value of constant\\’)
\neg: define(\\’PIE\\’,\\’3.14\\’);
\necho PIE;\/\/\/ will result to 3.14<\/p><\/blockquote>\n
\nif ($x==$y) {
\nconst CONST_VAL1 = \\’CONST\\’; \/\/ invalid produce error
\n}
\n\/\/ but
\nif ($x==$y) {
\ndefine(\\’CONST_VAL2\\’, \\’CONST\\’); \/\/ valid
\n}
\necho CONST_VAL1;\u00a0\/\/ produce error
\necho CONST_VAL2;<\/p>\n