Wireless sensor networks (WSNs) as powerful tools for information acquisition have been receiving wide attention. Due to size and cost restrictions of the sensor nodes, energy problem has been a fundamental constrain and challenge faced by many applications of WSNs. To solve the energy problem, researchers jointly apply the emerging techniques of wireless power transfer and intelligent mobile vehicles to develop a new paradigm of wireless rechargeable sensor networks (WRSNs). In designing WRSNs, a first and foremost problem is the charging programming capability. A well-designed charging programming can maintain a WRSN working continuously at a low cost. This paper surveys the latest research on charging programming in WRSNs from 6 different dimensions. In each dimension, different types of charging programming are analyzed and compared. Based on these analyses, design principles in different applications are proposed. These principles are applied to design charging programming in 3 realistic WSNs and the usability of these principles is demonstrated.