每个name值加pex，age加5， 原数据：

$data=[
    ["name"=>'a','age'=>12],
    ["name"=>'b','age'=>22],
    ["name"=>'c','age'=>33],
    ["name"=>'d','age'=>44],
];

 实现效果

方案一、foreach引用方式

$data=[
    ["name"=>'a','age'=>12],
    ["name"=>'b','age'=>22],
    ["name"=>'c','age'=>33],
    ["name"=>'d','age'=>44],
];

foreach ($data as &$v){
    $v['name']="pex".$v['name'];
    $v['age']=$v['age']+5;
}
var_dump($data);

 方案二、foreach通过key改变原数组值

$data=[
    ["name"=>'a','age'=>12],
    ["name"=>'b','age'=>22],
    ["name"=>'c','age'=>33],
    ["name"=>'d','age'=>44],
];

foreach ($data as $k=>$v){
    $data[$k]['name']="pex".$v['name'];
    $data[$k]['age']=$v['age']+5;
}
var_dump($data);

方案三、使用传统的for循环修改数组元素：

$data = [
    ["name" => 'a', 'age' => 12],
    ["name" => 'b', 'age' => 22],
    ["name" => 'c', 'age' => 33],
    ["name" => 'd', 'age' => 44],
];
for ($i = 0; $i < count($data); $i++) {
    $data[$i]['name'] = "pex" . $data[$i]['name'];
    $data[$i]['age'] = $data[$i]['age']+5;
}
var_dump($data);

方案四、使用 foreach 循环副本修改数组元素：

$data = [
    ["name" => 'a', 'age' => 12],
    ["name" => 'b', 'age' => 22],
    ["name" => 'c', 'age' => 33],
    ["name" => 'd', 'age' => 44],
];
$newData = [];
foreach ($data as $item) {
    $item['name'] = "pex" . $item['name'];
    $item['age'] = $item['age']+5;
    $newData[] = $item;
}
var_dump($newData);

方案五、使用 array_map 函数修改数组元素：

<?php

$data = [
    ["name" => 'a', 'age' => 12],
    ["name" => 'b', 'age' => 22],
    ["name" => 'c', 'age' => 33],
    ["name" => 'd', 'age' => 44],
];
$newData = array_map(function ($item) {
    $item['name'] = "pex" . $item['name'];
    $item['age'] =  $item['age']+5;
    return $item;
}, $data);
var_dump($newData);