如何让我的 C 程序计数不止一个字符？

Question

我正在尝试使用标准 C 函数编写一个接收文件和字符串的程序，该程序计算字符串包含的文件中的所有字符。

例如，如果用户写：

counter.exe x.txt abcd

程序计算文件x.txt中字符串包含的每个字符的个数：a, b ,c ,d

示例消息：

Number of 'a' characters in 'x.txt' file is: 12
Number of 'b' characters in 'x.txt' file is: 0
Number of 'c' characters in 'x.txt' file is: 3
Number of 'd' characters in 'x.txt' file is: 5

到目前为止，我已经能够让它打印并计算文件中的一个字符，我如何让它计算我告诉它计算的所有字符，而不仅仅是字符串中的第一个字符？

counter.c代码：

#include<stdio.h>

int main() {

    int count = 0;
    char sf[20]; char rr; FILE* fp; char c;

    printf("Enter the file name :\n");
    gets(sf);

    printf("Enter the character to be counted :\n");
    scanf("%c", &rr);
    fp = fopen(sf, "r");

    while ((c = fgetc(fp)) != EOF)
    {
        if (c == rr)
            count++;
    }
    printf("File '%s' has %d instances of letter '%c'.", sf, count, rr);

    fclose(fp);
    return 0;
}

Answer 1

#define  SIZE 1024
char * malloc_buff(int dim){
    char *buf;
    buf=malloc(sizeof(char)*dim);
    if(buf==NULL){
        perror("Error in malloc");
    }
    return buf;
}


char * read_file(char * file){
    FILE* fd;
    char* file_pt;
    file_pt=malloc_buff(SIZE);
    errno=0;
    fd=fopen(file,"r+");
    if(errno!=0){
        fprintf(stderr,"error open file\n");
        exit(-1);
    }
    fread(file_pt,sizeof(char),SIZE,fd);
    if(fclose(fd)){
        fprintf(stderr,"errore close file\n");
        exit(-1);
    }
    return file_pt;
}
int main(int argc, char *argv[])
{
    char* content;
    content=malloc_buff(SIZE);
    content=read_file(argv[1]);
    int lenght_word=strlen(argv[2]);
    int counter[lenght_word];
    int i=0,x=0;
    for(x=0;x<lenght_word;x++){
        counter[x]=0;
    }
    while (content[i]!='\0'){
        for(x=0;x<lenght_word;x++){
            if (content[i]==argv[2][x]){
                counter[x]++;
            }
        }
        i++;
    }
    for(x=0;x<lenght_word;x++){
        printf("The values are: for %c is %d",argv[2][x],counter[x]);
    }
    return 0;
}

Answer 2

几种解决方案：

1. 为您的main() 函数提供一些输入并解析这些，请参阅here
2. 在放置 scanf() 和另一个 while 循环（以及您需要的其他内容）的位置再执行一次 while 循环。
3. 例如，如果您想要 4 个字母，则实现一个 for 循环并将 scanf() 放入其中，将值存储在一个数组中。然后，您必须添加 4 个不同的计数器，这些计数器在下一个 while 循环中的 4 个不同测试中更新。

顺便说一句，如果您需要此程序用于其他目的而不仅仅是练习，那么您的系统中有很多已经实现的命令可以做到这一点，例如grep。

Answer 3

您可以使用strpbrk 和查找表：

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

int main(void) 
{
    char *text = "Sample input bla bla bla"; // your file contents
    const char *find = "abcd"; // your argv[2]
    int lookup[127] = {0}; // the lookup table

    while (*text)
    {
        char str[2] = {*text, 0};
        char *ptr = strpbrk(str, find);

        if (ptr != NULL) // if found
        {
            if ((*ptr >= 0) && (*ptr < 128))
            {
                lookup[(int)*ptr]++; // increase position
            }
        }
        text++;
    }
    for (int i = 0; i < 128; i++)
    {
        if (lookup[i] != 0)
        {
            printf("%c: %d times\n", i, lookup[i]);
        }
    }
    return 0;
}

输出：

a: 4 times
b: 3 times

Answer 4

我假设您可以将文件读入一个大缓冲区或一次将一行读入一个较小的缓冲区。

void  CountChars( unsigned int *charCount, char *buffer, int bufferSize )
{
    unsigned int  i;

    for (i = 0; i < bufferSize; i++) {
        charCount[buffer[i]]++;
    }
}

void main( int argc, char **argv )
{
    unsigned int  charCount[256];
    int           i;
    char          buffer[8192];  /* Or whatever size you want to work with at a time */

    /* Initialize the character counts to zero */
    memset(charCount, 0, sizeof(charCount));

    /* Insert code to fill the buffer with the file data */

    /* Count the characters in the buffer */
    CountChars(charCount, buffer, sizeof(buffer));

    /* At that point, the array 'charCount' has the count of each byte that
       occurred in the buffer.  If the file is too large to fit in memory
       and you called it in the loop, then you only initial the charCount
       array to zero before the first call.  From this point, you can go
       through the loop to determine which of the character counts you might
       be interested in, or if you are interested in all the characters that
       occurred, you could do the following. */
    for (i = 0; i < sizeof(charCount) / sizeof(charCount[0]); i++) {
        if (charCount[i] > 0) {
            printf("'%c' -- %d\n", (char) i, charCount[i]);
        }
    }
}