C string append

by

You need to allocate new space as well. Consider this code fragment:

char * new_str ;
if((new_str = malloc(strlen(str1)+strlen(str2)+1)) != NULL){
    new_str[0] = '\0';   // ensures the memory is an empty string
    strcat(new_str,str1);
    strcat(new_str,str2);
} else {
    fprintf(STDERR,"malloc failed!\n");
    // exit?
}

You might want to consider strnlen(3) which is slightly safer.

Updated, see above. In some versions of the C runtime, the memory returned by malloc isn’t initialized to 0. Setting the first byte of new_str to zero ensures that it looks like an empty string to strcat.

More Related Contents:

  1. What is the output of the following code in C? [closed]
  2. pointer to string concept in c [closed]
  3. What is the difference between char s[] and char *s?
  4. Why is this string reversal C code causing a segmentation fault? [duplicate]
  5. How to use sscanf in loops?
  6. When should I use ampersand with scanf()
  7. enum to string in modern C++11 / C++14 / C++17 and future C++20
  8. How do I create an array of strings in C?
  9. How to convert enum names to string in c
  10. Are string literals const?
  11. Returning string from C function
  12. How to compare strings in an “if” statement? [duplicate]
  13. fgets() includes the newline at the end [duplicate]
  14. What is the proper way of implementing a good “itoa()” function?
  15. What is a “wide character string” in C language?
  16. Print all the permutations of a string in C
  17. Comparing two strings in C? [duplicate]
  18. Array type char[] is not assignable [duplicate]
  19. Why is adding a leading space in a scanf format string recommended?
  20. Conversion of Char to Binary in C
  21. C’s strtok() and read only string literals
  22. Concatenating strings in C, which method is more efficient?
  23. How can I convert an int to a string in C?
  24. String.indexOf function in C
  25. Does C support raw string literals?
  26. Does C have any tools for doing string addition?
  27. Creating C formatted strings (not printing them)
  28. C split a char array into different variables
  29. A possible algorithm for determining whether two strings are anagrams of one another? [closed]
  30. Counting words in a string – c programming

Leave a Comment