35. str_rot13
36. str_shuffle
37. str_split
38. str_word_count
39. strcasecmp
40. strstr
41. strcmp
42. strcspn
43. strip_tags
44. stripos
45. stripslashes
46. stristr
47. strlen
48. strnatcmp
49. strpbrk
50. strpos
51. strrchr
52. strrev