View Compilation Error

0_0_12679791_28470.cpp: In function `int main()':
0_0_12679791_28470.cpp:38: error: `chara' undeclared (first use this function)
0_0_12679791_28470.cpp:38: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_12679791_28470.cpp:38: error: `b' undeclared (first use this function)
0_0_12679791_28470.cpp:42: error: `a' undeclared (first use this function)
0_0_12679791_28470.cpp:50: error: `return0' undeclared (first use this function)