使用 sscanf 读取空间

Question

我正在尝试使用 sscanf 读取字符串，以便在拆分文件时将此扫描的字符串用作文件名。

问题是 sscanf 只读取文件中出现的第一个 space，这是正常情况。但是，我在 Stack Overflow 中看到了很多关于如何读取这些 spaces.

的技巧。

不幸的是，它们似乎都是一样的，只需在函数中添加一个%[^\t\n[=14=]]或类似的东西即可。

问题是这种方法对我不起作用，我无法确定原因；我尝试了在这里找到的所有技巧，其中 none 有效。

如果有人能帮我找出问题，我将不胜感激。

代码如下：

int TAM_BUFFER = 75; 
int filecounter=1, linecounter=1;

int main(int argc, char *argv[]){

    char fileoutputname[15];
    char buffer[TAM_BUFFER];
    char buffer2[15];
    char buffer3[15];

    FILE *arquivo = fopen("Entrada.txt", "r");
    FILE *saida;

    sprintf(fileoutputname, "%s.txt", buffer2);
    saida = fopen(fileoutputname, "w");

    if(arquivo != NULL){

        while(fgets(buffer, TAM_BUFFER, arquivo)){
            if(linecounter==2){
                strncpy(buffer2,buffer,sizeof buffer2 - 1);
                buffer2[sizeof buffer2 - 1] = '[=10=]';
            }

            if (strncmp(buffer,"NEWDAY",strlen("NEWDAY")) == 0){
                fclose(saida);
                linecounter = 1;
                filecounter++;
                sscanf(buffer2, "%s", &buffer3);
                printf("strlen(%s)=%d\n", buffer3, (int) strlen(buffer3));
                sprintf(fileoutputname, "%s.txt", buffer3);
                saida = fopen(fileoutputname, "w");
                if (!saida)
                    return 1;       
            }

            fprintf(saida,"%s\n", buffer);
            linecounter++;

        }
    }

    fclose(arquivo);
    fclose(saida);
    return 0;
}

*我想做的是获取文件的第二行并使用前 14 个字符作为文件名。

文件的输入是这个：

TAM 2000-03-07T14:00    22.78   5.50999 2   786 2.8 798 2.8 186 0.0 298 3.2
TAM 2000-03-08T14:01    22.78   5.50999 2   779 1.2 793 1.0 186 0.0 300 1.5
TAM 2000-03-07T14:02    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9
TAM 2000-03-07T14:03    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9
TAM 2000-03-07T14:04    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9
TAM 2000-03-17T14:05    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9
TAM 2000-03-07T14:06    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9
NEWDAY
TAM 2000-03-08T14:09    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9
TAM 2000-03-07T14:10    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9
TAM 2000-03-07T14:11    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9
TAM 2000-03-09T14:12    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9
NEWDAY
TAM 2000-03-09T14:13    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9
TAM 2000-03-31T14:14    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9
TAM 2000-03-01T14:15    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9
TAM 2000-03-01T14:16    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9
TAM 2000-03-01T14:17    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9
TAM 2000-03-01T14:18    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9
TAM 2000-03-02T14:19    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9

Answer 1

如果你决定放弃 sscanf()，你可以用 fgets() 代替..

#include <stdio.h>

int main()
{
    char buffer2[200] = "Name with Spaces";

    FILE *fp;
    fp = fmemopen (buffer2, strlen (buffer2), "r"); 

    char str[200];
    if ( fgets(str, 200, fp) != NULL ) 
    {
        printf("Scanned Name: %s \n", str );
    }
}

Answer 2

基本如：

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

int TAM_BUFFER = 75; 

int main(int argc, char *argv[]){
    char fileoutputname[15] = {0};
    char buffer[TAM_BUFFER];

    FILE *arquivo = fopen("Entrada.txt", "r");
    FILE *saida;

    if(arquivo == NULL){
        perror("fopen");
        exit(EXIT_FAILURE);
    }

    fscanf(arquivo, "%14c", fileoutputname);//first split file name
    saida = fopen(fileoutputname, "w");
    rewind(arquivo);

    while(fgets(buffer, sizeof buffer, arquivo)){
        if(strncmp(buffer,"NEWDAY", 6) == 0){ // strlen("NEWDAY") is 6
            long file_pos = ftell(arquivo);//or use fgetpos for large file, save file position
            fscanf(arquivo, "%14c", fileoutputname);//next file name
            fseek(arquivo, file_pos, SEEK_SET);//or use fsetpos (pair with fgetpos), restore file position
            saida = freopen(fileoutputname, "w", saida);//fclose(saida);saida=fopen(fileoutputname, "w");
        }
        fprintf(saida,"%s", buffer);//No add newline
    }
    fclose(arquivo);
    fclose(saida);
    return 0;
}

Answer 3

如评论中所述，您有许多字符串对于您声明的数组来说太长了。具体来说，您的数据文件行长 75 个字符，无法放入 75 个字符缓冲区。进行更改并稍微调整变量名称，您可以执行以下操作：

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

enum { BUFL = 20, TAMB = 80 };

int main (int argc, char **argv) {

    int fcnt = 1, lcnt = 1;
    char buf[TAMB] = "", buf2[BUFL] = "", buf3[BUFL] = "";
    char ofn[BUFL] = "";
    FILE *ifp = argc > 1 ? fopen (argv[1], "r") : stdin;
    FILE *ofp = argc > 2 ? fopen (argv[2], "w") : stdout;
    if (!ifp || !ofp) {
        fprintf (stderr, "error: file open failed.\n");
        return 1;
    }

    while (fgets (buf, TAMB, ifp)) {
        char *p = buf;
        for (; *p && *p !='\n'; p++) {} /* remove trailing \n */
        if (*p) *p = 0; /* overwrite '\n' with nul-terminator */

        if (lcnt == 2) {
            strncpy (buf2, buf, BUFL - 1);
            buf2[BUFL - 1] = 0;
        }

        if (strncmp (buf, "NEWDAY", strlen("NEWDAY")) == 0) {
            fclose (ofp);
            lcnt = 1;
            fcnt++;
            // sscanf (buf2, "%s", &buf3);
            strcpy (buf3, buf2);
            printf ("strlen (%s) = %zu\n", buf3, strlen (buf3));
            sprintf (ofn, "%s.txt", buf3);
            ofp = fopen (ofn, "w");
            if (!ofp)
                return 1;       
        }
        fprintf (ofp, "%s\n", buf);
        lcnt++;
    }

    if (ifp != stdin) fclose (ifp);

    return 0;
}

示例输入文件

$ cat dat/newday.txt
TAM 2000-03-07T14:00    22.78   5.50999 2   786 2.8 798 2.8 186 0.0 298 3.2
TAM 2000-03-08T14:01    22.78   5.50999 2   779 1.2 793 1.0 186 0.0 300 1.5
TAM 2000-03-07T14:02    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9
TAM 2000-03-07T14:03    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9
TAM 2000-03-07T14:04    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9
TAM 2000-03-17T14:05    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9
TAM 2000-03-07T14:06    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9
NEWDAY
TAM 2000-03-08T14:09    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9
TAM 2000-03-07T14:10    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9
TAM 2000-03-07T14:11    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9
TAM 2000-03-09T14:12    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9
NEWDAY
TAM 2000-03-09T14:13    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9
TAM 2000-03-31T14:14    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9
TAM 2000-03-01T14:15    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9
TAM 2000-03-01T14:16    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9
TAM 2000-03-01T14:17    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9
TAM 2000-03-01T14:18    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9
TAM 2000-03-02T14:19    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9

示例Use/Output 文件

$ ./bin/readspaces dat/newday.txt dat/newdayout.txt
strlen (TAM 2000-03-08T14:0) = 19
strlen (TAM 2000-03-08T14:0) = 19

$ cat dat/newdayout.txt
TAM 2000-03-07T14:00    22.78   5.50999 2   786 2.8 798 2.8 186 0.0 298 3.2

TAM 2000-03-08T14:01    22.78   5.50999 2   779 1.2 793 1.0 186 0.0 300 1.5

TAM 2000-03-07T14:02    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9

TAM 2000-03-07T14:03    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9

TAM 2000-03-07T14:04    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9

TAM 2000-03-17T14:05    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9

TAM 2000-03-07T14:06    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9


$ cat TAM\ 2000-03-08T14\:0.txt
NEWDAY

TAM 2000-03-09T14:13    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9

TAM 2000-03-31T14:14    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9

TAM 2000-03-01T14:15    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9

TAM 2000-03-01T14:16    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9

TAM 2000-03-01T14:17    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9

TAM 2000-03-01T14:18    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9

TAM 2000-03-02T14:19    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9

(注意： 存在额外的行是因为您未能 trim '\n' 阅读并包含在 buf 中 fgets)

修复换行问题后，您的输出文件为：

$ cat TAM\ 2000-03-08T14\:0.txt
NEWDAY
TAM 2000-03-09T14:13    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9
TAM 2000-03-31T14:14    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9
TAM 2000-03-01T14:15    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9
TAM 2000-03-01T14:16    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9
TAM 2000-03-01T14:17    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9
TAM 2000-03-01T14:18    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9
TAM 2000-03-02T14:19    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9

查看更改，如果您有任何问题，请告诉我。目前尚不清楚您尝试使用 buffer2/3 大小达到的长度，但您可以调整 BUFL 常量以使其满足您的需求。另请注意，您可以简单地将 buffer2 复制到 buffer3，不需要 snprintf 语句。

它确实显示 15 间隔为代码的 outputfilename 部分产生了所需的结果。将 BUFL 更改为 15 提供：

$ ./bin/readspaces dat/newday.txt dat/newdayout.txt
strlen (TAM 2000-03-08) = 14
strlen (TAM 2000-03-08) = 14

然后生成输出文件：

$ cat TAM\ 2000-03-08.txt
xt
TAM 2000-03-09T14:13    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9
TAM 2000-03-31T14:14    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9
TAM 2000-03-01T14:15    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9
TAM 2000-03-01T14:16    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9
TAM 2000-03-01T14:17    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9
TAM 2000-03-01T14:18    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9
TAM 2000-03-02T14:19    22.78   5.50999 2   773 3.0 788 3.8 186 0.1 300 0.9

(注意： 但是，输出文件开头的 NEWDAY 的一些未定义行为不是 xt)

使用 sscanf 读取空间

Reading spaces with sscanf

c

string

space

file

scanf