如何使用空格和换行符遍历文本文件，对每个字符串执行函数，然后以原始格式再次打印出来？

考虑将其编写为过滤器，处理 和 .这极大地简化了代码！以下内容将满足您的需求，并迅速而沉着！stdinstdout

#include <stdio.h>
#include <ctype.h>

char *procWrd( char *word ) {
    static char obuf[ 64 ];
    sprintf( obuf, "%s-%.2s", word, word );
    return obuf;
}

int main( void ) {
    int ch;
    char word[ 64 ]; // big enough!
    int wrdChr = 0;

    while( ( ch = getchar() ) != EOF )
        if( isspace( (unsigned char)ch ) ) { // guaranteed LF at EOF
            if( wrdChr ) {
                word[ wrdChr ] = '\0'; // terminate string
                printf( "%s", procWrd( word ) ); // output modified version
                wrdChr = 0; // reset
            }
            putchar( ch ); // output whitespace
        } else
            word[ wrdChr++ ] = ch; // buffer characters of word

    return 0;
}

我调整每个单词的版本如下所示：

fire-fi dwarf-dw stone-st
rock-ro beer-be arrow-ar lion-li
sword-sw shield-sh
archstone-ar
dragon-dr gold-go
silver-si
hall-ha
goblet-go chest-ch axe-ax

运行文件两次以获得真正的乐趣：
猫文件.txt |项目 |prog > outfile.txt

使用 和 ：fgets()strspn()strcspn()

#include <ctype.h>
#include <stdio.h>
#include <string.h>

static const char whisp[] = " \t\n";

static void mapper(size_t n_bytes, char *data)
{
    for (size_t i = 0; i < n_bytes; i++)
    {
        unsigned char c = data[i];
        if (isupper(c))
            data[i] = tolower(c);
        else if (islower(c))
            data[i] = toupper(c);
        /* else leave alone */
    }
}

int main(void)
{
    char line[2048];
    while (fgets(line, sizeof(line), stdin))
    {
        char *data = line;
        char *eol = line + strlen(line);
        size_t n_bytes;
        while (data < eol)
        {
            if ((n_bytes = strspn(data, whisp)) > 0)
            {
                fwrite(data, n_bytes, 1, stdout);
                data += n_bytes;
            }
            if ((n_bytes = strcspn(data, whisp)) > 0)
            {
                mapper(n_bytes, data);
                fwrite(data, n_bytes, 1, stdout);
                data += n_bytes;
            }
        }
    }
    return 0;
}

使用“读取空格”循环的代码：

/* SO 7719-2181 */
#include <ctype.h>
#include <stdio.h>
#include <string.h>

static void mapper(size_t n_bytes, char *data)
{
    for (size_t i = 0; i < n_bytes; i++)
    {
        unsigned char c = data[i];
        if (isupper(c))
            data[i] = tolower(c);
        else if (islower(c))
            data[i] = toupper(c);
        /* else leave alone */
    }
}

int main(void)
{
    char line[1024];
    while (scanf("%1023s", line) == 1)
    {
        mapper(strlen(line), line);
        fputs(line, stdout);
        int c;
        while ((c = getchar()) != EOF && isspace(c))
            putchar(c);
        if (c != EOF)
            ungetc(c, stdin);
    }
    return 0;
}

两者都对标准输入进行大小写转换，将其写入标准输出。例如，在其源代码上运行第二个程序会产生：

/* so 7719-2181 */
#INCLUDE <CTYPE.H>
#INCLUDE <STDIO.H>
#INCLUDE <STRING.H>

STATIC VOID MAPPER(SIZE_T N_BYTES, CHAR *DATA)
{
    FOR (SIZE_T I = 0; I < N_BYTES; I++)
    {
        UNSIGNED CHAR C = DATA[I];
        IF (ISUPPER(C))
            DATA[I] = TOLOWER(C);
        ELSE IF (ISLOWER(C))
            DATA[I] = TOUPPER(C);
        /* ELSE LEAVE ALONE */
    }
}

INT MAIN(VOID)
{
    CHAR LINE[1024];
    WHILE (SCANF("%1023S", LINE) == 1)
    {
        MAPPER(STRLEN(LINE), LINE);
        FPUTS(LINE, STDOUT);
        INT C;
        WHILE ((C = GETCHAR()) != eof && ISSPACE(C))
            PUTCHAR(C);
        IF (C != eof)
            UNGETC(C, STDIN);
    }
    RETURN 0;
}

（两次出现 被转换为 ，并转换为 。代码的其余部分为大写，但标点符号保持不变。EOFeofSOso

代码不会对输出操作进行错误检查——严格来说，它应该这样做。