https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67154
Bug ID: 67154 Summary: sscanf does not extract correct value when the format is "%c" and the location is of type int* Product: gcc Version: 5.2.0 Status: UNCONFIRMED Severity: critical Priority: P3 Component: libgcc Assignee: unassigned at gcc dot gnu.org Reporter: wondertx at gmail dot com Target Milestone: --- #include <iostream> #include <string> #include <cstdio> using std::cout; using std::endl; int main() { std::string s { 'a', 'b', 'c' }; cout << s << endl; int a; int b, c; int ret; ret = sscanf(s.c_str(), "%c%c%c", &a, &b, &c); cout << a << ' ' << b << ' ' << c << endl; cout << "ret " << ret << endl; return 0; } The output is: abc 97 4197986 99 ret 3 Output of gcc -v : Using built-in specs. COLLECT_GCC=gcc COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-unknown-linux-gnu/5.2.0/lto-wrapper Target: x86_64-unknown-linux-gnu Configured with: /build/gcc/src/gcc-5.2.0/configure --prefix=/usr --libdir=/usr/lib --libexecdir=/usr/lib --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=https://bugs.archlinux.org/ --enable-languages=c,c++,ada,fortran,go,lto,objc,obj-c++ --enable-shared --enable-threads=posix --enable-libmpx --with-system-zlib --with-isl --enable-__cxa_atexit --disable-libunwind-exceptions --enable-clocale=gnu --disable-libstdcxx-pch --disable-libssp --enable-gnu-unique-object --enable-linker-build-id --enable-lto --enable-plugin --enable-install-libiberty --with-linker-hash-style=gnu --enable-gnu-indirect-function --disable-multilib --disable-werror --enable-checking=release --with-default-libstdcxx-abi=gcc4-compatible Thread model: posix gcc version 5.2.0 (GCC)