c语言程序设计案例教程（第2版）笔记（六）—字符串处理实例

字符串处理

• 功能描述：从键盘输入一个文本行后，为用户提供菜单选择，实现字符串一些操作——显示文本行、查找并替换指定子串、删除指定子串、统计指定子串数目。
• 实现代码：

 #include<stdio.h>
 #include<string.h>
 #include<stdlib.h>
 #pragma warning(disable:4996)
 
 #define NUM 256
 
 void displayMenu();
 int choiceItem();
 void searchReplace(char *buf, char *s, char *t);
 void deleteString(char *buf, char *s);
 int totle(char *buf, char *s);
 
 main()
 {
     char buf[NUM];
     char s[], t[];
     int choice;
 
     system("cls");
     printf("Enter a text line : ");   /*输入待操作文本行*/
     gets(buf);
     do{
         choice = choiceItem();    /*选择菜单项*/
         switch (choice){
         case :
             printf("Search:");
             gets(s);
             printf("\nReplace:");
             gets(t);
             searchReplace(buf, s, t);
             printf("\nThe result is %s\n", buf);
             break;
         case :
             printf("\nDelete:");
             gets(s);
             deleteString(buf, s);
             printf("\nThe result is %s\n", buf);
             break;
         case :
             printf("\nSearch:");
             gets(s);
             printf("\nThe counts of %s is %d\n", s, totle(buf, s));
             break;
         case :
             printf("\nThe string is %s\n", buf);
             break;
         }
     } while (choice != );
     printf("\n\nBey!");
 }
 
 void displayMenu()   /*显示菜单*/
 {
     printf("\n==========MENU===========\n");
     printf("1............Search/Replace");
     printf("\n2............Delete");
     printf("\n3............Totle");
     printf("\n4............Display");
     printf("\n0............Exit\n");
     printf("\nChoice:\n");
 }
 
 int choiceItem()   /*菜单选择*/
 {
     int choice;
     char line[];
 
     do{
         displayMenu();
         gets(line);
         choice = atoi(line);   /*将字符串转化为整型*/
     } while (choice< || choice>);
     return choice;
 }
 
 void searchReplace(char *buf, char *s, char *t)   /*查找替换子串*/
 {
     char m[];   /*内部缓冲区*/
     char *searchPtr = NULL;
     do{
         searchPtr = strstr(buf, s);   /*查找子串*/
         if (searchPtr != NULL){
             strcpy(m, searchPtr + strlen(s));   /*将子串后面的字符串备份到m中*/
             strcpy(searchPtr, t);
             strcpy(searchPtr + strlen(t), m);
         }
     } while (searchPtr != NULL);
 }
 
 void deleteString(char *buf, char *s)   /*删除子串*/
 {
     char *searchPtr = NULL;
     do{
         searchPtr = strstr(buf, s);   /*查找子串*/
         if (searchPtr != NULL){
             strcpy(searchPtr, searchPtr + strlen(s));
         }
     } while (searchPtr != NULL);
 }
 
 int totle(char *buf, char *s)   /*统计子串出现的次数*/
 {
     int n = ;
     char *searchPtr = NULL;
     do{
         searchPtr = strstr(buf, s);   /*查找子串*/
         if (searchPtr != NULL){
             n++;
             buf = searchPtr + strlen(s);   /*改变查找的初始位置*/
         }
     } while (searchPtr != NULL);
     return n;
 }