qt 读取segy文件

以下两段代码，是实际程序中截取的。你理解一下就行。

QString MainWindow::EBD2QStr(char *source){ QString result char * dest dest = (char*)malloc(3240) for (int i = 0i<3200i++){// *dest++ = *source++ EBCDIC2ASCII((unsigned char)*source++,dest) dest++ if (!((i+1)%80) &&i>0){ *dest = '\n' dest++ }} dest=dest - 3240 result = QString::fromLatin1(dest,3240) free(dest) return result}char MainWindow::EBCDIC2ASCII(unsigned char ebcdic,char* dest){ char * result result = dest char a2e[256] = {0, 1, 2, 3, 55, 45, 46, 47, 22, 5, 37, 11, 12, 13, 14, 15, 16, 17, 18, 19, 60, 61, 50, 38, 24, 25, 63, 39, 28, 29, 30, 31, 64, 79,127,123, 91,108, 80,125, 77, 93, 92, 78,107, 96, 75, 97, 240,241,242,243,244,245,246,247,248,249,122, 94, 76,126,110,111, 124,193,194,195,196,197,198,199,200,201,209,210,211,212,213,214, 215,216,217,226,227,228,229,230,231,232,233, 74,224, 90, 95,109, 121,129,130,131,132,133,134,135,136,137,145,146,147,148,149,150, 151,152,153,162,163,164,165,166,167,168,169,192,106,208,161, 7, 32, 33, 34, 35, 36, 21, 6, 23, 40, 41, 42, 43, 44, 9, 10, 27, 48, 49, 26, 51, 52, 53, 54, 8, 56, 57, 58, 59, 4, 20, 62,225, 65, 66, 67, 68, 69, 70, 71, 72, 73, 81, 82, 83, 84, 85, 86, 87, 88, 89, 98, 99,100,101,102,103,104,105,112,113,114,115,116,117, 118,119,120,128,138,139,140,141,142,143,144,154,155,156,157,158, 159,160,170,171,172,173,174,175,176,177,178,179,180,181,182,183, 184,185,186,187,188,189,190,191,202,203,204,205,206,207,218,219, 220,221,222,223,234,235,236,237,238,239,250,251,252,253,254,255 } char e2a[256] = {0, 1, 2, 3,156, 9,134,127,151,141,142, 11, 12, 13, 14, 15, 16, 17, 18, 19,157,133, 8,135, 24, 25,146,143, 28, 29, 30, 31, 128,129,130,131,132, 10, 23, 27,136,137,138,139,140, 5, 6, 7, 144,145, 22,147,148,149,150, 4,152,153,154,155, 20, 21,158, 26, 32,160,161,162,163,164,165,166,167,168, 91, 46, 60, 40, 43, 33, 38,169,170,171,172,173,174,175,176,177, 93, 36, 42, 41, 59, 94, 45, 47,178,179,180,181,182,183,184,185,124, 44, 37, 95, 62, 63, 186,187,188,189,190,191,192,193,194, 96, 58, 35, 64, 39, 61, 34, 195, 97, 98, 99,100,101,102,103,104,105,196,197,198,199,200,201, 202,106,107,108,109,110,111,112,113,114,203,204,205,206,207,208, 209,126,115,116,117,118,119,120,121,122,210,211,212,213,214,215, 216,217,218,219,220,221,222,223,224,225,226,227,228,229,230,231, 123, 65, 66, 67, 68, 69, 70, 71, 72, 73,232,233,234,235,236,237, 125, 74, 75, 76, 77, 78, 79, 80, 81, 82,238,239,240,241,242,243, 92,159, 83, 84, 85, 86, 87, 88, 89, 90,244,245,246,247,248,249, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57,250,251,252,253,254,255 } *dest = e2a[ebcdic] return *result}

fread是一个函数。从一个文件流中读数据，最多读取count个元素，每个元素size字节，如果调用成功返回实际读取到的元素个数，如果不成功或读到文件末尾返回0。函数原型size_tfread(void*buffer,size_tsize,size_tcount,FILE*stream)参数buffer用于接收数据的内存地址size要读的每个数据项的字节数，单位是字节count要读count个数据项，每个数据项size个字节.stream输入流返回值实际读取的元素个数。如果返回值与count不相同，则可能文件结尾或发生错误。从ferror和feof获取错误信息或检测是否到达文件结尾。

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