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[80], t[80];
    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 1:
            printf("Search:");
            gets(s);
            printf("
Replace:");
            gets(t);
            searchReplace(buf, s, t);
            printf("
The result is %s
", buf);
            break;
        case 2:
            printf("
Delete:");
            gets(s);
            deleteString(buf, s);
            printf("
The result is %s
", buf);
            break;
        case 3:
            printf("
Search:");
            gets(s);
            printf("
The counts of %s is %d
", s, totle(buf, s));
            break;
        case 4:
            printf("
The string is %s
", buf);
            break;
        }
    } while (choice != 0);
    printf("

Bey!");
}

void displayMenu()   /*显示菜单*/
{
    printf("
==========MENU===========
");
    printf("1............Search/Replace");
    printf("
2............Delete");
    printf("
3............Totle");
    printf("
4............Display");
    printf("
0............Exit
");
    printf("
Choice:
");
}

int choiceItem()   /*菜单选择*/
{
    int choice;
    char line[80];

    do{
        displayMenu();
        gets(line);
        choice = atoi(line);   /*将字符串转化为整型*/
    } while (choice<0 || choice>4);
    return choice;
}

void searchReplace(char *buf, char *s, char *t)   /*查找替换子串*/
{
    char m[256];   /*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 = 0;
    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;
}