我编写了一些代码来从二进制文件中读取第一个 pos
字节并将其写入另一个文件中。结果我运行时遇到了段错误。这是代码:
void outputUntillPos(const char * inFileName, const char * outFileName, int pos) {
FILE * inFile = fopen(inFileName, "r");
FILE * outFile = fopen(outFileName, "aw");
char buf[1024];
int read = 0;
int remain = pos;
do {
if(remain <= 1024) {
read = fread(buf, 1, pos, inFile);
} else {
read = fread(buf, 1, 1024, inFile);
}
remain -= read;
fwrite(buf, 1, read, outFile);
memset(buf, 0, 1024);
} while(remain > 0);
}
我是否在这里进行了超出范围的操作?
编辑:感谢所有帮助,这是编辑后的代码。
void outputUntillPos(const char * inFileName, const char * outFileName, int pos) {
FILE * inFile = fopen(inFileName, "r");
FILE * outFile = fopen(outFileName, "aw");
char buf[1024];
int read = 0;
int remain = pos;
if((inFile != NULL) && (outFile != NULL)) {
do {
if(remain <= 1024) {
read = fread(buf, 1, remain, inFile);
} else {
read = fread(buf, 1, 1024, inFile);
}
remain -= read;
fwrite(buf, 1, read, outFile);
memset(buf, 0, 1024);
} while(remain > 0 && read > 0);
}
fclose(inFile);
fclose(outFile);
}
最佳答案
当 remain
变为 <= 1024 并且输入 block 的 if
部分时,您将读取 pos
字节,如果大于 1024 时将写入缓冲区末尾。这就是导致段错误的原因。
您想在此处使用remain
:
if(remain <= 1024) {
read = fread(buf, 1, remain, inFile);
} else {
read = fread(buf, 1, 1024, inFile);
}
另外,在返回之前请务必检查 fopen
的返回值,以及 fclose(inFile)
和 fclose(outFile)
.
关于C - 段错误(核心转储),从文件中读取前 N 个字节,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/35348392/