work/source: In function ‘int main(int, char**)’:
work/source:80:29: error: ‘fopen’ was not declared in this scope
work/source:82:22: error: ‘fscanf’ was not declared in this scope
work/source:122:38: error: ‘fprintf’ was not declared in this scope
work/source:142:14: error: ‘fclose’ was not declared in this scope
work/source:144:20: warning: ignoring return value of ‘int system(const char*)’, declared with attribute warn_unused_result [-Wunused-result]
