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我有一個奇怪的問題,試圖用open(),read()和write()來讀寫9k字節。當我試圖將9k寫入文件並讀回時,數據只能達到2250字節。之後,一切都是零。iOS上的read()/ write()調用似乎受2250字節限制
這裏是我的代碼(除了是不相關的,我只是把它用NSDocumentDirectory文件名):
int fp = open([appFile cStringUsingEncoding:NSASCIIStringEncoding], O_RDWR | O_CREAT, 0644);
[_detailViewController log:@"first open() returns %i (err: %i)", fp, errno];
int data2[10000];
int data3[10000];
for (int i=0;i<10000;i++) data2[i] = 1;
[_detailViewController log:@"resetting seek to 0"];
int seekPos = lseek(fp, 0, SEEK_SET);
result = write(fp, data2, 9000);
[_detailViewController log:@"wrote 9k, result is %i", result];
[_detailViewController log:@"resetting seek to 0"];
seekPos = lseek(fp, 0, SEEK_SET);
result = read(fp, data3, 9000);
[_detailViewController log:@"read 9k, result is %i", result];
[_detailViewController log:@"values of data2[2248-2252] = 0x%x 0x%x 0x%x 0x%x 0x%x", data2[2248], data2[2249], data2[2250], data2[2251], data2[2252]];
[_detailViewController log:@"values of data3[2248-2252] = 0x%x 0x%x 0x%x 0x%x 0x%x", data3[2248], data3[2249], data3[2250], data3[2251], data3[2252]];
close(fp);
這裏是陌生的輸出:
2013-02-13 14:08:38.290 FileTester[2800:907] first open() returns 6 (err: 3)
2013-02-13 14:08:38.295 FileTester[2800:907] resetting seek to 0
2013-02-13 14:08:38.301 FileTester[2800:907] wrote 9k, result is 9000
2013-02-13 14:08:38.306 FileTester[2800:907] resetting seek to 0
2013-02-13 14:08:38.311 FileTester[2800:907] read 9k, result is 9000
2013-02-13 14:08:38.319 FileTester[2800:907] values of data2[2248-2252] = 0x1 0x1 0x1 0x1 0x1
2013-02-13 14:08:38.327 FileTester[2800:907] values of data3[2248-2252] = 0x1 0x1 0x0 0x0 0x0
正如您在最後一行所看到的,數據突然變爲零。
任何想法,我可能做錯了什麼?真正讓我感到意外的是read()和write()返回9000.
9000字節== 2250整數(在此架構上)。 – ughoavgfhw 2013-02-13 19:42:21
謝謝,解決了它(: – Locksleyu 2013-02-15 18:18:25