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putchar is a function in C programming language that writes a single character to the standard output. Its prototype is as follows:

int putchar (int character)

The character to be printed is fed into the function as an argument, and if the writing is successful, the argument character is returned. Otherwise, end-of-file is returned.

The putchar function is specified in the C standard library header file stdio.h.

Sample usage

The following program uses getchar to read characters into an array and print them out using the putchar function after an end-of-file character is found.

#include <stdio.h>
int main() {
  char str;
  int n = 0;
  while (!feof(stdin)) {
    str = getchar();
    ++n;
  }
  for (int i = 0; i < n; ++i) {
    putchar(str);
  }
  return 0;
}

The function specifies the reading length's maximum value at 1000 characters; however if the end-of-file character doesn't come up after 1000 characters are read, different operating systems and different compilers will give different results: Some cases will terminate the program at a segmentation fault, while some others will read the remaining string into the non-allocated area of the memory, possibly causing errors to other programs.

See also

• stdio.h
• C standard library
• getchar

References

• putchar on Cplusplus.com

• C standard library