类型转换

1、linux下itoa的替代 

  char   temp[256];   
  sprintf(temp,"%d",value);

下面是转换的实例：

 

#include<stdio.h>
#include<fcntl.h>
#include<syscall.h>
#define PERMS 0777

void error(char *,...);

main(int argc, char *argv[])
{
    int f1, f2, n;
    char buf[BUFSIZ];

    if(argc != 3)
        error("Usage: cp from to");
    if((f1 = open(argv[1], O_RDONLY, 0)) == -1)
        error("cp: can't open %s",argv[1])
//the first method ,set the output length.

/*
    while ((n = read(f1, buf, BUFSIZ)) > 0){
        buf[n] = '\0';
        printf("-->%s",buf);
    }
*/
//the second method

    char formatstr[20];
    while ((n = read(f1, buf, BUFSIZ)) > 0){
        sprintf(formatstr,"-->%%.%ds",n);
        printf(formatstr,buf);
    }
    if((f1 = open(argv[1], O_RDONLY, 0)) == -1)
        error("cp: can't open %s",argv[1]);
    if((f2 = creat(argv[2], PERMS)) == -1)
        error("cp: can't create %s,mode %03o",
            argv[2],PERMS);
    while ((n = read(f1, buf, BUFSIZ)) > 0)
        if(write(f2, buf, n) != n)
            error("cp: write error onfile %s",argv[2]);
    return 0;
}