In the absence of an IDE, it is necessary to remember the function names, parameters, basic usage, and considerations of some commonly used library functions.
Referring to the Linux_c_hs.chm directory, I have roughly divided the usual functions into several categories:
- 1. Memory and string control and operation
- 2. String conversions
- 3. Character test
- 4. File operation
- 5. Time and date
- 6. Common mathematical functions
- 7. File Content operation
- 8. File Permissions Control
- 9. Process Operations
- 10. Threading Operations
- One. Socket operation
- 12. Signal Processing
- 13. Data structures and algorithms
/*Time Function Collation * * Function name usage remarks **1.char *asctime (const struct TM *tm); Obtain the TM first, and then the string format indicates that the thread is unsafe, there is a secure version plus _r**2.char *ctime (const time_t *TIMEP); Parameter up**3 can be obtained directly from time (). struct TM *gmtime (const time_t *TIMEP); Convert between formats thread unsafe **4.STRUCT TM *localtime (const time_t *TIMEP); NT up**5.time_t mktime (struct TM *tm); NT nt**6.time_t Time (time_t *tloc); NT is first called **7. int gettimeofday (struct timeval *tv, struct timezone *tz); NT gets time **8. int settimeofday (const struct Timeval *tv, const struct timezone *tz); NT set time **9. size_t strftime (char *s, size_t max, const char *format, const struct TM *TM); NT time converted to a string that can be formatted as specified **/
- Classification of common mathematical functions
/* Common Mathematical Functions collation * * function name usage Note **1. int abs (int j); To find the absolute value of an integer NT,GCC compilation requires-lm**2. Float Ceilf (float x); Minimum integer value of not less than parameter nt**3.double exp (double x); Calculates the X-square value of the base e nt**4. Double log (double x); Calculates an e-based X-pair value nt**5. Double sqrt (double x); Calculates the square root value nt**6.double pow (double x, double y); Calculates the X-based y-square value nt**7. Double log10 (double x); Calculates an X-pair value of 10 at the bottom of the NT* /
- Data structure and algorithm classification
/* data structure and algorithm collation * * function name usage remarks **1.char *crypt (const char *key, const char *salt); Encrypted data thread is unsafe, there is a secure version _R,GCC compilation required to add-lcrypt**2.void qsort (void *base, size_t nmemb, size_t size, int (*compar) (const void *, const void *)); The comparison function can be based on integers or char to do similar strcmp functions to support various data types of fast-row **3.int rand_r (unsigned int *seedp); Generate random number seeds in general, the parameters can be filled in time (NULL), the seed is different random values **4.int rand (void); The random value in [0, Rand_max] cannot be re-entered, there is a secure version _r** /
The above is a summary of time-date functions, mathematical functions, algorithm functions and so on.
The next step is to summarize the sockets, threads, processes, and signals.
Summarize and organize the common library functions of C language in Linux----time and date math and algorithm