練習3.2

編一個函數escape(s,t)，將字符串t複製到s中，並在複製過程中將換行符、製表符轉換成\n\t可見字符。

再編寫一個具有相反功能的函數。

 

代碼：

#include <stdio.h>
#include <stdlib.h>

void escape(char *s, const char *t);
void rescape(char *s, const char *t);
int main(int argc, char *argv[])
{
    char s[30] = "";
    char t[20] = "hello world\\t!\\n";
    escape(s, t);
    rescape(s, t);

    printf("%s", s);
    return 0;
}

void escape(char *s, const char *t)
{
    size_t j = 0;
    for (size_t i = 0; t[i] != '\0'; ++i) {
        switch (t[i]) {
            case '\t':
                {
                    s[j++] = '\\';
                    s[j++] = 't';
                    break;
                }
            case '\n':
                {
                    s[j++] = '\\';
                    s[j++] = 'n';
                    break;
                }
            case ' ':
                {
                    s[j++] = '#';
                    break;
                }
            default:
                s[j++] = t[i];
        }
    }
    s[j++] = '\0';
}

void rescape(char *s, const char *t)
{
    size_t j = 0;
    for (size_t i = 0; t[i] != '\0'; ++i) {
        switch (t[i]) {
            case '\\':
                {
                    if (t[i+1] == 't') {
                        ++i;
                        s[j++] = '\t';
                    } else if (t[i+1] == 'n') {
                        ++i;
                        s[j++] = '\n';
                    } else {
                        s[j++] = '\\';
                    }
                }
                break;
            default:
                {
                    s[j++] = t[i];
                }
        }
    }
    s[j++] = '\0';
}