从不兼容的指针类型传递 fwrite 的参数 4答案

【问题标题】：Passing argument 4 of fwrite from incompatible pointer type从不兼容的指针类型传递 fwrite 的参数 4
【发布时间】：2020-04-06 16:18:26
【问题描述】：

我想将源文件的内容复制到目标文件中，但收到以下警告：

warning: passing argument 4 of ‘fwrite’ from incompatible pointer type [-Wincompatible-pointer-types]

fwrite(target, sizeof(char), targetSize, sourceContent);

如果我忽略警告，我会遇到分段错误。

FILE *source = fopen(argv[1], "r");
FILE *target = fopen(argv[2], "w");

if (source == NULL || target == NULL) {
    printf("One or both files do NOT exist\n");
    abort();
}

fseek(source, 0, SEEK_END);
long sourceSize = ftell(source);

fseek(source, 0, SEEK_SET);
char *sourceContent = (char *)malloc(sourceSize);
fread(sourceContent, sizeof(char), sourceSize, source);


long targetSize = sourceSize;
fwrite(target, sizeof(char), targetSize, sourceContent);

【问题讨论】：

标签： c fwrite gcc-warning

【解决方案1】：

fread() and fwrite() 都将要读取/写入的缓冲区作为 first 参数，将文件作为第四个参数。

// This is fine.
fread(sourceContent, sizeof(char), sourceSize, source);
// Swap the first and fourth argument in the fwrite call.
fwrite(sourceContent, sizeof(char), targetSize, target);

【讨论】：