而循环VS的foreach循环

Question

我试着将其打印在Excel中，但我不明白为什么foreach循环给我一个警告：非法串偏移但while循环它只是平稳运行

这是while循环

EDITED

include 'db.php'; 
$sql = "SELECT * FROM customer"; 
$result = mysql_query($sql); 
$excel = array(); 

while($row = mysql_fetch_array($result)){ 
    $wew = $row["fname"]."\t".$row["lname"]."\t".$row["email"]; 
    array_push($excel,$wew); 
} 

echo implode("\n",array_values($excel)); 

这是我foreach循环

include 'db.php'; 
$sql = "SELECT * FROM customer"; 
$result = mysql_query($sql); 
$row = mysql_fetch_array($result); 
$excel = array(); 

foreach($row as $r){ 
    $wew = $r["fname"]."\t".$r["lname"]."\t".$r["email"]; 
    array_push($excel,$wew); 
} 

echo implode("\n",array_values($excel)); 

我试着去了解它，但怎么也找不到解决这个问题之一。

Answer 1

你$r是string型，而不是array这样的：

foreach($row as $r){ 
    $wew = $row["fname"]."\t".$row["lname"]."\t".$row["email"]; 
    array_push($excel,$wew); 
} 

OR

$wew = ""; 
foreach($row as $r){ 
    $wew .= $row["fname"]."\t".$row["lname"]."\t".$row["email"]; 
} 
array_push($excel,$wew);