《c程序设计语言》第一章 导言 部分代码

1-1_hello.c

#include
main()
{
    printf("Hello,world!");
}


1-2_fahr.c
华氏温度和设施温度的转换
#include
main()
{
    int fahr,celsius;
    int lower,upper,step;
    lower = 0;
    upper = 300;
    step = 20;
    fahr = lower;
    while (fahr <= upper){
        celsius = 5 * (fahr-32)/9;
        printf("%d\t%d\n",fahr,celsius);
        fahr = fahr + step;
    }
}

执行结果：
$ ./1-2_fahr.exe
0       -17
20      -6
40      4
60      15
80      26
100     37
120     48
140     60
160     71
180     82
200     93
220     104
240     115
260     126
280     137
300     148


1-4_count.c
单词计数
#include
#define IN 1
#define OUT 0

main()
{
    int c,nl,nw,nc,state;
    state = OUT;
    nl = nw = nc = 0;
    while ((c = getchar()) != EOF){
        ++nc;
        if (c == '\n')
            ++nl;
        if (c ==' ' || c == '\n' || c == '\t')
            state = OUT;
        else if (state == OUT){
            state = IN;
            ++nw;
        }
    }
    printf("%d %d %d\n",nl,nw,nc);
}


1-9_lines.c
查找最长的行，并打印出来：


#include
#define MAXLINE 1000 /* maximum input line length */
int getline(char line[], int maxline);
void copy(char to[], char from[]);

/* print the longest input line */
main()
{
    int len; /* current line length */
    int max; /* maximum length seen so far */
    char line[MAXLINE]; /* current input line */
    char longest[MAXLINE]; /* longest line saved here */
    max = 0;
    while ((len = getline(line, MAXLINE)) > 0)
    if (len > max) {
        max = len;
        copy(longest, line);
    }
    if (max > 0) /* there was a line */
        printf("%s", longest);
    return 0;
}
/* getline: read a line into s, return length */
int getline(char s[],int lim)
{
    int c, i;
    for (i=0; i < lim-1 && (c=getchar())!=EOF && c!='\n'; ++i)
        s[i] = c;
    if (c == '\n') {
        s[i] = c;
    ++i;
    }
    s[i] = '\0';
    return i;
}
/* copy: copy 'from' into 'to'; assume to is big enough */
void copy(char to[], char from[])
{
    int i;
    i = 0;
    while ((to[i] = from[i]) != '\0')
        ++i;
}