Re: How to truncate char string fromt beginning and replace chars in string by other chars in C or C++?

Hongyu <>
Thu, 7 Aug 2008 12:38:52 -0700 (PDT)
On Aug 7, 3:31 pm, Victor Bazarov <> wrote:

Hongyu wrote:


I have a datetime char string returned from ctime_r, and it is in th=


format like ""Wed Jun 30 21:49:08 1993\n\0", which has 26 chars
including the last terminate char '\0', and i would like to remove the
weekday information that is "Wed" here, and I also would like to
replace the spaces char by "_" and also remove the "\n" char. I didn't
know how to truncate the string from beginning or replace some chars
in a string with another chars without using a loop through one char
by one char of the string. I used the below code to achieve
replacement of " " by "_" and also removed the last "\n" char, without
considering removing the first 4 chars i.e. weekday information yet.
But even this I still didn't get what i like. Below is the code i

#include <time.h>
#include <stdio.h>

int main(void)
   time_t ltime;
   char buf[50];

   // Get the time

   // The datetime string returned by ctime_r is in the format
   // of "Wed Jun 30 21:49:08 1993\n\0"
   printf("The time is: %s", ctime_r(&ltime, buf));

   // replace the " " and ":" in the datetime string
   // by "_"
   buf[7] = "_"; // " ", line 18

For a single symbol you need to use single quotes:

     buf[7] = '_';

(same everywhere).

   buf[10] = "_"; // " ", line 19
   buf[13] = "_"; // ":", line 20
   buf[16] = "_"; // ":", line 21
   buf[19] = "_"; // " ", line 22
   buf[24] = "\0"; // remove the last \n char, line 23

   // printf the new datetimestring
   printf("The time is: %s", buf);


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Thanks a lot for the prompty help, Victor. It worked! The compiler
errors disappered and the space was replaced by '-'. Can you also tell
me how to remove the chars in the beginning of the string? and how to
remove a char inside the string, because i have one more space inside
the string and would like to remove it. I tried to use like:
buf[0]='', but got compiler errors like: test_ctimer.c:18:12: empty
character constant

Thanks a lot.

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