c语言快速copy,c语言copy函数实现

#includeint readFile(char *fname,char *buff);

int writeFile(char *fname,char *buff);

int main(int argc,char *argv[])

{

FILE *fd;

int i;

int ch;

char *buf = NULL;

buf = (char*)malloc(sizeof(char)*1024*1000*20);

if(argc != 3)

{

printf("Usage copy source dest\n");

exit(1);

}

if(access(argv[1],R_OK|F_OK) < 0)

{

printf("%s cannot read or file not found！",argv[1]);

exit(1);

}

if(strcmp(argv[1],argv[2]) == 0)

{

printf("%s cannot copy the same file！",argv[1]);

exit(1);

}

readFile(argv[1],buf);

writeFile(argv[2],buf);

}

/** 读源文件 **/

int readFile(char *fname,char *buff)

{

FILE *fp;

char ch;

int i=0;

if((fp=fopen(fname,"rb")) == NULL)

{

perror("open log file error");

return -1;

}

while(!feof(fp))

{

ch=fgetc(fp);

buff[i]=ch;

i++;

}

buff[i] = '\0';

fclose(fp);

return 0;

}

/** 写入目标文件 **/

int writeFile(char *fname,char *buff)

{

int fd;

size_t len;

if((fd = open(fname,O_WRONLY|O_CREAT|O_TRUNC,S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH)) < 0)

{

perror("open log file error");

return -1;

}

len = strlen(buff);

printf("%c",len);

if(write(fd,buff,(int)len) < 1)

{

perror("write log error");

return -1;

}

close(fd);

return 0;

}