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发表于 2020-2-11 14:39:16
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# S1E2:第一个程序
## 测试题
0. 为什么我们说计算机其实是“二傻子”?
1. CPU 唯一认识的语言是什么语言?
2. C 语言编写的源代码转换为汇编语言的过程叫什么?
3. 编译型语言和解释型语言的本质区别是什么?
4. 在 Linux 系统上用 C 语言编译的可执行程序,是否能在 Windows 系统上执行?
5. 解释型编程语言是如何实现跨平台的?
6. 莫斯密码的原理其实是什么?
7. 视频中小甲鱼“故弄玄虚”的那段密文还原后是什么内容(中文)?

## 动动手
0. 不是说一个合格的程序员需要累积 10 万行的代码量嘛!
那么这节课的动动手环节就让大家写一个计算代码量的程序吧~
程序要求:统计当前目录及所有子目录下,C 语言源文件的代码总行数。
Linux 和 MacOS:
```c
#include <stdio.h>
#include <unistd.h>
#include <dirent.h>
#include <string.h>
#include <stdlib.h>
#include <sys/stat.h>
#define MAX 256
long total;
int countLines(const char *filename);
int isCode(const char *filename);
void findAllDirs(const char *path);
int countLines(const char *filename)
{
FILE *fp;
int count = 0;
int temp;
if ((fp = fopen(filename, "r")) == NULL)
{
fprintf(stderr, "Can not open the file: %s\n", filename);
return 0;
}
while ((temp = fgetc(fp)) != EOF)
{
if (temp == '\n')
{
count++;
}
}
fclose(fp);
return count;
}
int isCode(const char *filename)
{
int length;
length = strlen(filename);
if (!strcmp(filename + (length - 2), ".c"))
{
return 1;
}
else
{
return 0;
}
}
void findAllDirs(const char *path)
{
DIR *dp;
struct dirent *entry;
struct stat statbuf;
if ((dp = opendir(path)) == NULL)
{
fprintf(stderr, "The path %s is wrong!\n", path);
return;
}
chdir(path);
while ((entry = readdir(dp)) != NULL)
{
lstat(entry->d_name, &statbuf);
if (!strcmp(".", entry->d_name) || !strcmp("..", entry->d_name))
continue;
if (S_ISDIR(statbuf.st_mode))
{
findAllDirs(entry->d_name);
}
else
{
if (isCode(entry->d_name))
{
total += countLines(entry->d_name);
}
}
}
chdir("..");
closedir(dp);
}
int main()
{
char path[MAX] = ".";
printf("计算中...\n");
findAllDirs(path);
printf("目前你总共写了 %ld 行代码!\n\n", total);
return 0;
}
```
Windows:
```c
#include <io.h>
#include <direct.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define MAX 256
long total;
int countLines(const char *filename);
void findAllCodes(const char *path);
void findALLFiles(const char *path);
int countLines(const char *filename)
{
FILE *fp;
int count = 0;
int temp;
if ((fp = fopen(filename, "r")) == NULL)
{
fprintf(stderr, "Can not open the file:%s\n", filename);
return 0;
}
while ((temp = fgetc(fp)) != EOF)
{
if (temp == '\n')
{
count++;
}
}
fclose(fp);
return count;
}
void findAllCodes(const char *path)
{
struct _finddata_t fa;
long handle;
char thePath[MAX], target[MAX];
strcpy(thePath, path);
if((handle = _findfirst(strcat(thePath, "/*.c"), &fa)) != -1L)
{
do
{
sprintf(target, "%s/%s", path, fa.name);
total += countLines(target);
}while (_findnext(handle, &fa) == 0);
}
_findclose(handle);
}
void findALLDirs(const char *path)
{
struct _finddata_t fa;
long handle;
char thePath[MAX];
strcpy(thePath, path);
if((handle = _findfirst(strcat(thePath, "/*"), &fa)) == -1L)
{
fprintf(stderr, "The path %s is wrong!\n",path);
return;
}
do
{
if (!strcmp(fa.name, ".") || !strcmp(fa.name, ".."))
continue;
if( fa.attrib == _A_SUBDIR)
{
sprintf(thePath, "%s/%s", path, fa.name);
findAllCodes(thePath);
findALLDirs(thePath);
}
}while (_findnext(handle, &fa) == 0);
_findclose(handle);
}
int main()
{
char path[MAX] = ".";
printf("计算中...\n");
findAllCodes(path);
findALLDirs(path);
printf("目前你总共写了 %ld 行代码!\n\n", total);
system("pause");
return 0;
}
```
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