C4 - 4.1 Basics of Functions

 

Chapter 4 - Functions and Program Structure

第4章 函数与程序结构

 

4.1 Basics of Functions

4.1 函数的基本知识

 

模式匹配的例子：

#include<stdio.h>

int getline(char *s1, int lim){
    char *sp;
    sp = s1;
    while(lim > 1 && (*sp = getchar()) != EOF && *sp != '\n'){
        lim--;
        sp++;
    }
    if(*sp == '\n')
        sp++;
    *sp = '\0';
    return sp - s1;
}

int strindex(const char *s1, const char *s2){
    const char *s3, *sp1, *sp2;
    s3 = s1;
    while(*s1){
        sp1 = s1; sp2 = s2;
        while(*sp1 == *sp2 && *sp1 != '\0'){
            sp1++; sp2++;
        }
        if(*sp2 == '\0')
            return s1 - s3;
        s1++;
    }
}

int main(){
    char s1[300], s2[100];
    char c;
    
    scanf("%s", s2);

    while((c = getchar()) == '\n')
        ;
    ungetc(c, stdin);
    
    while(getline(s1, 300) > 0){
        if(strindex(s1, s2) >= 0)
            printf("%s", s1);
    }
}