Printf Error Return
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Return Type Of Printf In C
Overflow the company Business Learn more about hiring developers or posting ads with us Stack Overflow Questions Jobs what would a scanf() function returns? Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community of 6.2 million programmers, just like you, helping each other. Join them; how can we achieve run time polymorphism in c++? it only takes a minute: Sign up Return value of printf() function in C up vote 11 down vote favorite 7 The printf() function will return the number of characters printed. But in the code below why is it printing 5. int a=1000; printf("%d",printf("\n%d",a)); It prints "1000" once and a space, so altogether we have 2 characters. It should
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output "1000 2". But its outputting "1000 5". c share|improve this question edited Oct 4 '12 at 15:49 Derek 779627 asked Aug 14 '11 at 8:49 Angus 2,966195496 add a comment| 9 Answers 9 active oldest votes up vote 24 down vote accepted The number of characters output is 5. 1000 is four characters. \n is one character. printf doesn't return the number of "items" output like the scanf family of functions do for input. It returns the actual character count. share|improve this answer answered Aug 14 '11 at 8:51 Mat 136k21235274 add a comment| up vote 5 down vote The inner call happens first, prints 5 characters (\n, 1, 0, 0, 0) and returns 5. The outer call then happens, and prints the 5 that was returned by the inner call. share|improve this answer edited Aug 14 '11 at 8:59 answered Aug 14 '11 at 8:52 RichieHindle 147k34252334 add a comment| up vote 3 down vote suppose expression: int a=10; printf("a=%d",printf("b=%d",a)); output b=10 a=4; bbecause of value of assigned to b i.e b=10; and b,=,1,0 co
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community of 6.2 million programmers, just like you, helping each other. Join them; it only takes a minute: Sign up Why does printf return a value? up vote 10 down vote favorite 1 I know http://stackoverflow.com/questions/7055882/return-value-of-printf-function-in-c that printf returns a negative error or number of characters printed on success. Only reason to check this return value is if the execution of program somehow depends on the printf status. But I could not think of a scenario where this return value is useful. I, for one, have never checked the return value of printf function. What are the scenarios where return status from printf is useful? c printf http://stackoverflow.com/questions/13535557/why-does-printf-return-a-value share|improve this question asked Nov 23 '12 at 20:49 Rumple Stiltskin 3,2451018 add a comment| 6 Answers 6 active oldest votes up vote 11 down vote There are at least 2 uses of the return value of printf: To check for errors. This is rarely important when your output is interactive or purely informative, but for programs that are processing text from stdio or a file and writing the result to stdout, it's important to know whether an error (such as disk full, closed pipe, or dropped network connection) prevented the entire output from being written. This is especially important if the source file will be deleted/replaced by the output once the output is complete. However, due to buffering, checking the result of printf itself is usually not helpful. You'll want to check ferror(stdout) after writing the last output and flushing in order to get a reliable indication of whether any write errors occurred. On the other hand, checking the return value of printf allows you to detect failure early so you don't waste time attempting to write millions of lines when the first line already failed, so it can be a very useful check; it's just not a sufficient check by itself. If the number of characters output
have return values?UpdateCancelPromoted by Metavision.comWe compared 2D & 3D instructions to find out what performs betterRead on to understand how people https://www.quora.com/Do-printf-and-scanf-have-return-values complete tasks 20% faster with 3D AR instructions vs 2D instructions.Learn More at Metavision.comAnswer Wiki4 Answers Tapasweni Pathak, I can C, a bit.Updated 143w agoShort Answer:Yes, they have http://pubs.opengroup.org/onlinepubs/009695399/functions/fprintf.html return values.Long Answer:Upon successful return, printf function return the number of characters printed.If an output error is encountered, a negative value is returned.Sample code:#include
print formatted output SYNOPSIS #include <stdio.h>
int fprintf(FILE *restrict stream, const char *restrict format, ...);
int printf(const char *restrict format, ...);
int snprintf(char *restrict s, size_t n,
const char *restrict format, ...);
int sprintf(char *restrict s, const char *restrict format, ...);
DESCRIPTION [CX] The functionality described on this reference page is aligned with the ISOC standard. Any conflict between the requirements described here and the ISOC standard is unintentional. This volume of IEEEStd1003.1-2001 defers to the ISOC standard. The fprintf() function shall place output on the named output stream. The printf() function shall place output on the standard output stream stdout. The sprintf() function shall place output followed by the null byte, '\0', in consecutive bytes starting at *s; it is the user's responsibility to ensure that enough space is available. The snprintf() function shall be equivalent to sprintf(), with the addition of the n argument which states the size of the buffer referred to by s. If n is zero, nothing shall be written and s may be a null pointer. Otherwise, output bytes beyond the n-1st shall be discarded instead of being written to the array, and a null byte is written at the end of the bytes actually written into the array. If copying takes place between objects that overlap as a result of a call to sprintf() or snprintf(), the results are undefined. Each of these functions converts, formats, and prints its arguments under control of the format. The format is a character string, beginning and ending in its initial shift state, if any. The format is composed of zero or more directives: ordinary characters, which are simply copied to the output stream, and conversion specifications, each of which shall result in the fetching of zero or more arguments. The results are undefined if there are insufficient arguments for the format. If the format is exhausted wh