使用命令行参数的程序要求用户记住正确的使用方法。重新编写下面的程序，不使用命令行参数，而是提示用户键入所需的信息。
// reducto.c -- 把您的文件压缩为原来的三分之一！
#include <stdio.h>
#include <stdlib.h> // 为了调用exit()
#include <string.h> // 为strcpy()和strcat()函数提供原型
#define LEN 40
int main (int argc, char *argv[])
{
FILE *in, *out; // 声明两个FILE指针
int ch;
char name[LEN]; // 用于存储输入文件名
int count = 0;
// 检查命令行参数
if(argc < 2)
{
fprintf(stderr, "Usage: %s filename\n", argv[0]);
exit(1);
}
// 实现输入
if ((in = fopen(argv[1], "r")) == NULL)
{
fprintf(stderr, "I couldn't open the file \"%s\"\n",
argv[1]);
exit(2);
}
// 实现输出
strcpy(name, argv[1]); // 把文件名复制到数组中
strcat(name, ".red"); // 在文件名后添加.red
if((out = fopen (name, "w")) == NULL)
{ // 打开文件以供写入
fprintf(stderr, "Can't create output file.\n");
exit(3);
}
// 复制数据
while ((ch = getc(in)) != EOF)
if (count++ % 3 == 0)
putc(ch, out); // 打印每3个字符中的1个
// 收尾工作
if(fclose (in) != 0 || fclose (out) != 0)
fprintf(stderr, "Error in closing files\n");
return 0;
}
// reducto.c -- reduces your files by two-thirds! #include <stdio.h> #include <stdlib.h> // for exit() #include <string.h> // for strcpy(), strcat() #define LEN 40 int main(void) { FILE *in, *out; // declare two FILE pointers int ch; char name[LEN]; // storage for output filename int count = 0; // set up input puts("Enter the name of the file to be reduce"); gets(name); if ((in = fopen(name, "r")) == NULL) { fprintf(stderr, "I couldn't open the file \"%s\"\n", name); exit(2); } // set up output name[LEN - 5] = '\0'; strcat(name,".red"); // append .red if ((out = fopen(name, "w")) == NULL) { // open file for writing fprintf(stderr,"Can't create output file.\n"); exit(3); } // copy data while ((ch = getc(in)) != EOF) if (count++ % 3 == 0) putc(ch, out); // print every 3rd char // clean up if (fclose(in) != 0 || fclose(out) != 0) fprintf(stderr,"Error in closing files\n"); return 0; }