《Programming Abstractions In C》学习第52天,p130-p131,总结如下:
一、技术总结
1. pig latin game
通过pig latin game把握字符复制,指针遍历等操作。
/* * 输出:字符串,这里采纳书中坐着自定义的getline函数 */#include <stdio.h>#include <string.h>#include "simpio.h"#define MaxWord 1000static _Bool IsVowel(char ch); // 书中p34, if实用于非此即彼的两种抉择(two-way);如果有多个,那么就应用switch。static void PigLatin(char *word, char buffer[], int bufferSize);static char *FindFirstVowel(char *word); // *示意函数FindFirstVowel返回一个指向char的指针int main() { char *word; char translationBuffer[MaxWord + 1]; printf("Enter a word: "); word = GetLine(); PigLatin(word, translationBuffer, MaxWord + 1); printf("Pig Latin: %s\n", translationBuffer);}/* * Function:IsVowel * Usage: isVowel = IsVowel(character) * ----------------------------------- * 该函数判断字符是否是元音字母,如果是,返回True,否则返回False。 */_Bool IsVowel(char ch) { switch (ch) { case 'A': case 'E': case 'I': case 'O': case 'U': case 'a': case 'e': case 'i': case 'o': case 'u': return TRUE; default: return FALSE; }}/* * Function: PigLatin * Usage: PigLatin(word, buffer, bufferSize); * ------------------------------------------ * This function translate a word from English to Pig Latin. The * translated word is written into the array buffer, which has an * allocated size of bufferSize. The code checks for buffer * overflow and generate an error if it occurs. */static void PigLatin(char *word, char buffer[], int bufferSize) { char *vp; int wordLength; vp = FindFirstVowel(word); wordLength = strlen(word); if (vp == word) { wordLength += 3; } else if (vp != NULL) { wordLength += 2; } if (wordLength >= bufferSize) { Error("Buffer overflow"); } if (vp == NULL) { // 单词中不存在元音字母:不做任何批改 strcpy(buffer, word); } else if (vp == word) { // 单词以元音字母结尾: 在单词开端增加way(示例:any > anyway) strcpy(buffer, word); strcat(buffer, "way"); } else { // 单词以辅音字母结尾: (1)将辅音字母挪动到单词尾部,直到第一个字母是元音字母。 // (2)挪动实现后,在单词尾部增加ay(示例:trash > ashtray) strcpy(buffer, vp); strncat(buffer, word, vp - word); strcat(buffer, "ay"); }}/* * FindFirstVowel: 找出单词中的第一个元音字母 */static char *FindFirstVowel(char *word) { char *cp; // 将原来的指针赋值给新的指针,防止原来的指针被批改 // 遍历指针 for (cp = word; *cp != '\0'; cp++) { // 留神:在这里*cp示意的是值 if (IsVowel(*cp)) { return cp; // 留神:cp++挪动之后,cp指向的地址扭转了 } } return NULL; // 如果找不到,则返回空指针(NULL)}
残缺代码见:https://github.com/codists/Programming-Abstractions-In-C/tree/main/chapter3/piglatingame
二、英语总结
1.check用法剖析
答:p130,“The code checks for buffer overflow and gennerates an error if it occurs.”,记忆中check是及物动词,这里为何会跟for?check既能够用作及物动词(vi),也能够用作不及物动词(vt),意思是"to make certain that sth is corret by examinming it.”。
(1)vt.对xxx进行查看。示例:Customs stopped us and checked (= searched) our bags for alcohol and cigarettes(海关拦住了咱们,查看咱们的包里有没有烟酒)。
(2)vi.例如书中的用法。其实也能够改成及物动词的用法,The code check string length and buffersize for buffer overflow and gennerates an error if it occurs.代码对字符串的长度和buffer的大小进行查看(即判断字符串的长度与buffersize的大小关系),看是否存在缓冲区溢出的状况,如果存在,就报错。
2.up to 什么意思?
答:p129, "If the word begins with the consonant, the function extracts the string of consonant up to the first vowel, moves that collection of consonant to the end of the word"。
“up to”在这里的用法是“prep. until(直到)”,这里是两个词式的介词。
3.concern 什么意思?
答:p131, "Almost half the code in the function, however, is concerned with making sure that the buffer does not overflow.",concern在这里的意思是“vt. about”。
三、参考资料
1. 编程
(1)Eric S.Roberts,《Programming Abstractions in C》:https://book.douban.com/subject/2003414
2. 英语
(1)Etymology Dictionary:https://www.etymonline.com
(2) Cambridage Dictionary:https://dictionary.cambridge.org
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