Easy Tutorial
C Array Of Pointers C Standard Library Stdarg H C Exercise Example17 C Recursion C Function Tmpnam C Function Wctomb C Examples Lexicographical Order C Function Strncmp C Function Abs C Examples Alphabet C Examples Printf Int C Exercise Example26 C Exercise Example84 C Examples Write File C Function Div C Function Toupper C Exercise Example44 C Function Raise C Examples Quadratic Roots C Function Cos C Exercise Example75 C Examples Check Armstrong Number C Examples Output Array C Variables C Standard Library Ctype H C Examples Complex Number Add C Function Fgetpos C Exercise Example22 C Exercise Example69 C Examples Octal Decimal Convert C Exercise Example80 C Function Gmtime C Function Gets C Function Isgraph C Exercise Example58 C Type Casting C Exercise Example13 C Nested If C Function Puts C Command Line Arguments C Exercise Example98 C Examples Binary Decimal Convert C Exercise Example71 C If C Sort Algorithm C Examples Calculator Switch Case C Passing Arrays To Functions C Exercise Example40 C Function Atol C Function Localtime C Macro Edom C Function Putchar C Function Strncat C Function Scanf C Exercise Example6 C Function Signal C Examples Factors Number C Examples Fibonacci Series C Examples Add Matrix C Function Rewind C Function Strftime C Function Longjmp C Exercise Example94 C Function Clearerr C Exercise Example36 C Examples Five Fish Html C Exercise Example54 C Function Strcpy C Function Feof C Examples Divide Concatenation Array C Exercise Example65 C Examples Structure Store Information C Variable Arguments C Exercise Example90 C Examples Access Array Pointer C Examples Remainder Quotient C Function Mktime C Pointers C Examples Swapping Cyclic Order C Exercise Example79 C Exercise Example32 C Exercise Example2 C Function Frexp C Exercise Example48 C Function Strpbrk C Function Fwrite C Exercise Example61 C Examples C Fun Pointer Callback C Basic Syntax C Data Types C Function Tolower C Function Fflush C Exercise Example88 C Function Fseek C Function Sprintf C Function Perror C Examples Sum Array C Exercise Example50 C Macro Assert C Do While Loop C Goto Statement C Exercise Example7 C Examples Int Data Compare C Function Vsprintf C Function Qsort C Nested Switch C Examples String Copy C Exercise Example95 C Function Vprintf C Function Getc C Exercise Example37 C Function Pow C Function Putc C Function Call By Pointer C Function Sinh C Examples Source Code Output C Exercise Example55 C Function Fread C Examples Sum Prime Numbers C Exercise Example64 C Function Isprint C Examples Printf Float C Examples Vowel Consonant Frequency String C Exercise Example91 C Multi Dimensional Arrays C Examples Add Numbers C Macro Errno C Function Sscanf C Exercise Example33 C Examples Ascii Value Character C Exercise Example78 C Function Free C Exercise Example49 C Exercise Example3 C Break Statement C Function Getchar C Examples Matrix Transpose C Function Strtok C Function Setlocale C Function Log10 C Exercise Example60 C Macro Va_Start C Examples Printf Helloworld C Exercise Example89 C Pointer To Pointer C Function Wcstombs C Function Setbuf C Function Isalnum C Exercise Example51 C Standard Library Errno H C Strings C Function Sin C Examples Leap Year C Function Clock C Function Strspn C Return Pointer From Functions C Exercise Example16 C Function Memmove C Standard Library Time H C Enum C Exercise Example27 C Function Strtoul C Function Log C Function Strrchr C Exercise Example85 C Bit Fields C Exercise Example45 C Function Fabs C Function Atoi C Storage Classes C Function Memcpy C Examples Power Number C Function Ceil C Exercise Example74 C Exercise Example68 C Exercise Example23 C Function Fmod C Function Strerror C 100 Examples C Loops C Examples Table Style C Exercise Example81 C Exercise Example12 C Exercise Example59 C Typedef C Examples Palindrome Number C Exercise Example99 C Function Tanh C Function Getenv C Function Exit C Exercise Example70 C Function Fopen C Function Abort C Function Ldexp C Function Ispunct C Function Isdigit C Exercise Example41 C Intro C Environment Setup C Examples Reverse Sentence Recursion C Exercise Example5 C Function Ftell C Examples Frequency Character C Function Sqrt C Function System C Function Strstr C Examples Concatenate String C Structures C Exercise Example35 C Exercise Example97 C Standard Library Float H C Exercise Example57 C Examples Negative Positive Zero C Switch C Examples Dynamic Memory Allocation Largest C Examples Factorial C Function Rand C Examples String Length C Function Isalpha C Exercise Example66 C Standard Library String H C Examples Hcf Gcd C Examples Remove Characters String C Examples Copy Array C Function Realloc C Examples Average Arrays C Exercise Example31 C Exercise Example93 C Arrays C Function Memcmp C Function Ferror C Examples Lcm C Function Atan C Standard Library Stdlib H C Examples Time Structure C Exercise Example1 C Continue Statement C Exercise Example29 C Exercise Example62 C Examples Octal Binary Convert C Function Isxdigit C Function Cosh C Examples Multiplication Table C Exercise Example53 C Exercise Example18 C Pointer Arithmetic C Examples Reverse Number C Function Fgetc C Function Printf C Examples Product Numbers C Exercise Example14 C Function Bsearch C Function Asin C Exercise Example87 C Function Setvbuf C Nested Loops C Passing Pointers To Functions C Function Ldiv C Input Output C Functions C Exercise Example25 C Function Fprintf C Function Labs C Function Strxfrm C Function Iscntrl C Exercise Example47 C Examples For Even Odd C Scope Rules C Exercise Example76 C Function Mbtowc C Examples Array Largest Element C Function Fsetpos C Function Fputc C Function Memset C Function Atexit C Unions C Exercise Example83 C Examples Printf Double C Function Exp C Examples Sum Natural Numbers C Function Malloc C Exercise Example21 C Function Srand C Macro Va_End C Exercise Example10 C Exercise Example100 C Function Ctime C Exercise Example72 C Memory Management C Exercise Example39 C Function Mblen C While Loop C Preprocessors C Standard Library Limits H C Examples Prime Number C Function Localeconv C Function Strchr C Exercise Example43 C Exercise Example9 C Examples Even Odd C Exercise Example15 C Macro Offsetof C Macro Null C Function Difftime C Examples Pyramid Pattern C Exercise Example86 C Exercise Example24 C Program Structure C Examples Joseph Life Dead Game C Error Handling C Function Strtod C Function Calloc C Exercise Example46 C Function Strcat C Exercise Example77 C Function Freopen C Function Acos C Macro Va_Arg C Function Asctime C Constants C Exercise Example82 C Function Atan2 C Function Mbstowcs C Exercise Example20 C Function Strlen C Function Strcspn C Standard Library Stdio H C Quiz C Exercise Example11 C Function Isupper C Examples Largest Number Three C Function Rename C Function Strcmp C Exercise Example101 C Function Vfprintf C Exercise Example38 C Exercise Example73 C For Loop C Function Modf C Exercise Example8 C Function Call By Value C Function Time C Exercise Example42 C Return Arrays From Function C Operators C Function Strtol C Exercise Example4 C Exercise Example34 C Exercise Example96 C Header Files C Function Fscanf C Function Islower C Exercise Example56 C File Io C Standard Library Assert H C Examples Display Alphabets C Function Snprintf C Macro Erange C Examples Sizeof Operator C Exercise Example67 C Standard Library Setjmp H C Exercise Example30 C Examples Standard Deviation C Function Ungetc C Standard Library Math H C Function Isspace C Tutorial C If Else C Function Fgets C Exercise Example92 C Standard Library C Examples Smallest Array Element C Function Remove C Examples Vowel Consonant C Function Tmpfile C Examples Digits Count C Function Atof C Standard Library Stddef H C Examples Printf Char C Function Strcoll C Function Memchr C Function Strncpy C Standard Library Locale H C Function Floor C Macro Setjmp C Exercise Example63 C Exercise Example28 C Standard Library Signal H C Examples Swapping C Pointer To An Array C Exercise Example19 C Exercise Example52 C Decision C Function Fputs C Examples Read File C Function Fclose
❮ C Exercise Example51 C Strings ❯

C Standard Library - <errno.h>

Introduction

The errno.h header file of the C Standard Library defines the integer variable errno, which is set by system calls and indicates errors in certain library functions when an error event occurs. This macro expands to a modifiable lvalue of type int, so it can be read and modified by a program.

At program startup, errno is set to zero, and specific functions in the C Standard Library modify its value to some non-zero value to indicate certain types of errors. You can also modify its value or reset it to zero when appropriate.

The errno.h header file defines a series of macros representing different error codes, which should expand to integer constant expressions of type int.

Library Macros

The following table lists the macros defined in the errno.h header file:

Number Macro & Description
1 extern int errno <br>This macro, set by system calls, indicates what error occurred in certain library functions during an error event.
2 EDOM Domain Error <br>This macro represents a domain error, which occurs when the input parameter is outside the domain defined by mathematical functions, and errno is set to EDOM.
3 ERANGE Range Error <br>This macro represents a range error, which occurs when the input parameter is outside the range defined by mathematical functions, and errno is set to ERANGE.
❮ C Exercise Example51 C Strings ❯