我有這個圖像表示爲base64字符串，我已經粘貼在這裏： https://paste.ubuntu.com/23343680/ 裏面有一個圖像。我打電話一個這base64字符串沒有得到解碼
Convert.FromBase64String
，這讓我
{"Invalid length for a Base-64 char array or string."}
現在我已經使用這個網站http://codebeautify.org/base64-to-image-converter粘貼相同字符串，並將其呈現在數據就好圖像。 這是什麼，我在這裏做錯了，我需要得到一個字節[]，我將使圖像，但我不能。 謝謝。
你必須追加=，直到長度被4整除。只有這是一個有效的base64字符串。
這段代碼就可以了：
string s = "yourVeryLongBase64String";
if ((s.Length % 4) > 0)
{
int diff = 4 - (s.Length % 4);
s = s.PadRight(s.Length + diff, '=');
}
byte[] b = Convert.FromBase64String(s);
謝謝，這是做得很好。現在有一個問題，如果你看這個https://paste.ubuntu.com/23343796/並粘貼到瀏覽器上，它會顯示你的圖像，如果你使用這個代碼https：// paste .ubuntu.com/23343806 /（我寫的）保存base64轉換後的字節數組圖像並進行比較，圖像完全不是它在chrome中的樣子。你能告訴我發生了什麼事嗎？謝謝。 – user734028
我不知道。抱歉。 –
嗨，我發現你的代碼中的一個小錯誤，行int diff = s.Length％4; shud be int diff = 4 - （s.Length％4）; – user734028
string str = "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=";
byte[] arr = Convert.FromBase64String(str);
添加==在字符串的結尾。它會工作。你傳遞的輸入是無效的base64值
你喂什麼'Convert.FromBase64String'？說，你如何生成你通過該方法的字符串作爲參數 – Benj