c - 阅读文档并在该文档中查找特定单词

Question

我有以下文档:

WTPZ24 KNHC 032040
TCMEP4

TROPICAL STORM SIMON FORECAST/ADVISORY NUMBER   9
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP192014
2100 UTC FRI OCT 03 2014

THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.

TROPICAL STORM CENTER LOCATED NEAR 18.8N 110.6W AT 03/2100Z
POSITION ACCURATE WITHIN  20 NM

REPEAT...CENTER LOCATED NEAR 18.8N 110.6W AT 03/2100Z
AT 03/1800Z CENTER WAS LOCATED NEAR 18.6N 110.1W

FORECAST VALID 04/0600Z 19.2N 112.2W
MAX WIND  65 KT...GUSTS  80 KT.
64 KT... 10NE   0SE   0SW  10NW.
50 KT... 30NE  30SE  20SW  20NW.
34 KT... 50NE  50SE  40SW  40NW.

FORECAST VALID 04/1800Z 20.0N 114.3W
MAX WIND  75 KT...GUSTS  90 KT.
64 KT... 20NE  10SE  10SW  20NW.

我正在尝试用 C 编写一个程序，该程序将读取该文件并找到单词字符串 FORECast VALID。每当一行有“预测有效”字样时，我希望程序打印该行并在该行之前打印“===>”。对于文档的其余部分，我只希望它简单地打印该行。

程序的最终输出应如下所示:

REPEAT...CENTER LOCATED NEAR 18.8N 110.6W AT 03/2100Z
AT 03/1800Z CENTER WAS LOCATED NEAR 18.6N 110.1W

===>FORECAST VALID 04/0600Z 19.2N 112.2W
MAX WIND  65 KT...GUSTS  80 KT.
64 KT... 10NE   0SE   0SW  10NW.
50 KT... 30NE  30SE  20SW  20NW.
34 KT... 50NE  50SE  40SW  40NW.

===>FORECAST VALID 04/1800Z 20.0N 114.3W
MAX WIND  75 KT...GUSTS  90 KT.
64 KT... 20NE  10SE  10SW  20NW.

我确实有一些代码片段可以逐字打印文档而无需===>，但我只需要帮助如何从行中隔离出FORECAST VALID，以便将===>放在这些行中:

FILE *fr;            /* declare the file pointer */

main()
{
   int n;
   char line[800];
   char buf[255];
   fr = fopen ("wtnt23.knhc.201410141453", "rt");  /* open the file for reading */

   while(fgets(line, 800, fr) != NULL)
   {
    sscanf (line, "%s", buf);
    if (buf="FORECAST")
   {
       printf("===>%s",line);
   }
   else
   {
        printf("%s",line);
   }
   fclose(fr);  /* close the file prior to exiting the routine */
} /*of main*/

Answer 1

if (buf="FORECAST") 完全错误。它不是比较，您不能使用 =...

复制到 char 数组

你只需要这样做:

while(fgets(line, 800, fr) != NULL)
{
   if(0 == strncmp(line, "FORECAST VALID", strlen("FORECAST VALID")) )
   {
       printf("===>%s",line);
   }
   else
   {
        printf("%s",line);
   }
}