PHP中各种数据类型的区别和转换方法

标签：原理   变量   php   .执行过程   

<?php
$a = 7;
$b = 'abcdsfdf';
echo $a . $b;
?>

if (UNEXPECTED(Z_TYPE_P(op1) != IS_STRING)) {
if (Z_ISREF_P(op1)) {
   op1 = Z_REFVAL_P(op1);
if (Z_TYPE_P(op1) == IS_STRING) break;
}
ZEND_TRY_BINARY_OBJECT_OPERATION(ZEND_CONCAT, concat_function);
use_copy1 = zend_make_printable_zval(op1, &op1_copy);

<?php
$double = 5.2323;
echo (int)$double;
?>

bool settype ( mixed &$var , string $type )函数来实现变量类型转化，源码实现如下：

PHP_FUNCTION(settype)
{
    zval *var;
    char *type;
    size_t type_len = 0;
    if (zend_parse_parameters(ZEND_NUM_ARGS(), "zs", &var, &type, &type_len) == FAILURE) {
        return;
    }
    ZVAL_DEREF(var);
    if (!strcasecmp(type, "integer")) {
        convert_to_long(var);
    } else if (!strcasecmp(type, "int")) {
        convert_to_long(var);
    } else if (!strcasecmp(type, "float")) {
        convert_to_double(var);
    } else if (!strcasecmp(type, "double")) { /* deprecated */
        convert_to_double(var);
    } else if (!strcasecmp(type, "string")) {
        convert_to_string(var);
    } else if (!strcasecmp(type, "array")) {
        convert_to_array(var);
    } else if (!strcasecmp(type, "object")) {
        convert_to_object(var);
    } else if (!strcasecmp(type, "bool")) {
        convert_to_boolean(var);
    } else if (!strcasecmp(type, "boolean")) {
        convert_to_boolean(var);
    } else if (!strcasecmp(type, "null")) {
        convert_to_null(var);
    } else if (!strcasecmp(type, "resource")) {
        php_error_docref(NULL, E_WARNING, "Cannot convert to resource type");
        RETURN_FALSE;
    } else {
        php_error_docref(NULL, E_WARNING, "Invalid type");
        RETURN_FALSE;
    }
    RETVAL_TRUE;
}

PHP中各种数据类型的区别和转换方法

标签：原理   变量   php   .执行过程   

原文地址：http://blog.csdn.net/wab5168/article/details/47395497