Open a text file and count the occurrences of each letter.
Some of these programs count all characters (including punctuation), but some only count letters A to Z.
#include <fstream> #include <iostream> int main() { std::ifstream input("filename.txt", std::ios_base::binary); if (!input) { std::cerr << "error: can't open file\n"; return -1; } size_t count[256]; std::fill_n(count, 256, 0); for (char c; input.get(c); ++count[uint8_t(c)]) // process input file ; // empty loop body for (size_t i = 0; i < 256; ++i) { if (count[i] && isgraph(i)) // non-zero counts of printable characters { std::cout << char(i) << " = " << count[i] << '\n'; } } }
- Output:
when file contains “Hello, world!” (without quotes):
! = 1 , = 1 H = 1 d = 1 e = 1 l = 3 o = 2 r = 1 w = 1
Content is available under GNU Free Documentation License 1.2.
