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《The C Programming Language》答案（第八章）

P1

/** * Rewrite the program cat from Chapter 7 using read,  * write, open and close instead of their standard library * equivalents. Perform experiments to determine the * relative speed of the two versions. **/#include 
   
    #include 
    
     #include 
     
      #include 
      
       void filecopy(int form,int to){
       int n;    char buf[BUFSIZ];    while((n=read(from,buf,BUFSIZ))>0)        write(to,buf,n);}void error(char* fmt,...){
       va_list args;    va_start(args,fmt);    fprintf(stderr,"error: ");    vfprintf(stderr,fmt,args);    fprintf(stderr,"\n");    va_end(args);    exit(1);}int main(int argc,char* argv[]){
       int f;    void filecopy(int f1,int f2);    if(argc==1)        filecopy(0,1);    else        while(--argc>0)            if((f=open(*++argv,O_RDONLY))==-1){
                   error("cannot open file %s",*argv);                return 1;            }            else{
                   filecopy(f,1);                close(f);            }    return 0;}
      
     
    
   

P2-7

🐴

第八章 完

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