c++ - 2d collision detection issue -

i'm working on basic square-square collision detection system checks player , bunch of tiles. problem since works going through tiles starting top left tile (in stage) bottom right tile checks collisions tiles above , left of player before else. because of this, if you're moving left , against wall, stuck because corrects players y position tile above before x position tile left (or right). wondering how can go fixing this. collision code follows:

for(std::vector<tile*>::iterator tile = tiles.begin(); tile != tiles.end(); tile++) {     if((*tile)->tiletype == tile::tile_wall) {         float cx = character->getposition().x;         float cy = character->getposition().y;         float chw = character->halfwidth();         float chh = character->halfheight();         float thw = tile::tile_width/2;         float thh = tile::tile_height/2;         float dx = cx - ((*tile)->getposition().x);         float dy = cy - ((*tile)->getposition().y);         if(fabsf(dy) < chh + thh) {             if(fabsf(dx) < chw + thw) {                 float ox = chw + thw - fabsf(dx);                 float oy = chh + thh - fabsf(dy);                 if(ox > oy) {                     if(dy > 0) {                         character->setposition(cx, cy + oy);                     }                     else {                         character->setposition(cx, cy - oy);                     }                 }                 else {                     if(dx > 0) {                         character->setposition(cx + ox, cy);                     }                     else {                         character->setposition(cx - ox, cy);                     }                 }             }         }     } } 

also, optimization appreciated.