将输入中包含特定“模式”或字符串的各行打印出来

P57

#include <stdio.h>
#define MAXLINE 1000 /* maximum input line length */

int getline(char line[], int max);
int strindex(char source[], char searchfor[]);
char pattern[] = "ould";   /* pattern to search for */

/* find all lines matching pattern */
int main()
{
	char line[MAXLINE];
    int found = 0;
    while (getline(line, MAXLINE) > 0)
    if (strindex(line, pattern) >= 0) {
		printf("%s", line);
        found++;
    }
	return found;
}

/* getline:  get line into s, return length */
int getline(char s[], int lim)
{
	int c, i;
    i = 0;
    while (--lim > 0 && (c=getchar()) != EOF && c != '\n')
       s[i++] = c;
    if (c == '\n')
       s[i++] = c;
    s[i] = '\0';
    return i;
}

/* strindex:  return index of t in s, -1 if none */
int strindex(char s[], char t[])
{
	int i, j, k;
    for (i = 0; s[i] != '\0'; i++) {
		for (j=i, k=0; t[k]!='\0' && s[j]==t[k]; j++, k++)
			;
        if (k > 0 && t[k] == '\0')
        return i;
    }
    return -1;
}