关于datagridview中checkbox列在选中行的情况下无法操作值

这几天做项目的时候碰到了个小问题，在datagridview中实现对checkbox列的全选和反选功能。代码如下

                    //全选

             if (dataGridView1.Rows.Count > 0)

                foreach (DataGridViewRow dgvr in dataGridView1.Rows)

                {

                    (dgvr.Cells["checkbox列名称"] as DataGridViewCheckBoxCell).Value = true;

                }

                    //反选

              if(dataGridView1.Rows.Count>0)

                foreach (DataGridViewRow dgvr in dataGridView1.Rows)

                {

                    (dgvr.Cells["  checkbox列名称  "] as DataGridViewCheckBoxCell).Value = (bool)((dgvr.Cells["DeleteFile"] as DataGridViewCheckBoxCell).Value) ? false : true;

                }

    发现个问题就是在datagridview选中的那一行上checkbox的值并没有改变。经baidu和google了一下，发现在代码改变状态前，使其readonly变为true就能解决。原理不得而知，先记下来吧！改进后的代码如下：

             //全选

             if (dataGridView1.Rows.Count > 0)

                foreach (DataGridViewRow dgvr in dataGridView1.Rows)

                {

                     (dgvr.Cells[" checkbox列名称 "] as DataGridViewCheckBoxCell).ReadOnly = true;

                    (dgvr.Cells["checkbox列名称"] as DataGridViewCheckBoxCell).Value = true;

                               (dgvr.Cells[" checkbox列名称 "] as DataGridViewCheckBoxCell).ReadOnly = false;

                }

                    //反选

              if(dataGridView1.Rows.Count>0)

                foreach (DataGridViewRow dgvr in dataGridView1.Rows)

                {          

                    (dgvr.Cells["   checkbox列名称   "] as DataGridViewCheckBoxCell).ReadOnly = true;

                    (dgvr.Cells["  checkbox列名称  "] as DataGridViewCheckBoxCell).Value = (bool)((dgvr.Cells["DeleteFile"] as DataGridViewCheckBoxCell).Value) ? false : true;

                    (dgvr.Cells["   checkbox列名称   "] as DataGridViewCheckBoxCell).ReadOnly = false;

                }